All the laws of physics are expressed in terms of physical quantities.
Scalar: Those have only magnitude eg. Distance ( measured in metre), time(sec), current (ampere), temperature (Kelvin), luminous intensity (candela), mass (kg), amount of substance (mole).
Vector quantities: Those which have direction and magnitude eg.
1. Displacement vs Distance
Distance is the actual length of path travelled by a moving body.
Displacement is the shortest distance the initial and final position of the body, along with the direction.
Distance travelled by you to reach study iq = 3+4+7= 14 units but displacement is the length of the dotted line joining your home and institute directing towards south-east.
2. Velocity: defines Speed along with direction of motion of body.
3. Acceleration : rate of change of velocity with respect to time.
Newton’s Laws of Motion:
I. A body at rest will remain at rest and a body in motion will continue to remain in motion until an external force is applied to it.
Concept of Inertia : A body resist change in its state of rest or of uniform motion.
a. Inertia of Rest
b. Inertia of Motion.
c. Inertia of Direction.
II. F (measured in newton) = m X a
Or
We can say, Force applied to a body is directly proportional to the rate of change of momentum (momentum = mass X velocity) which is produced by body.
III. Every action has an equal and opposite reaction. That means When two bodies act upon one another, their total momentum remains constant provided no external force is applied to it.
Concept of friction :
Some force acting on a stationary object which opposes its motion. This is Friction. Its of 3 types:
a. Static friction : exerted by object at rest
b. Sliding (also called Dynamic or Kinetic friction): exerted when object slides over a surface.
c. Rolling: exerted when an object rolls over a surface.
Static > Sliding > Rolling
Circular motion: When a body moves around a fixed point in a circular path with uniform speed.
Note that circular motion is accelerated even though the speed of body remains constant.
Projectile motion: A falling object having a horizontal velocity is called a projectile, and it moves in a curved path called parabola. It Possesses :
A horizontal motion with constant velocity.
A vertical motion with constant acceleration.
Note that: it is the gravitational attraction of the sun which keeps the planets revolving around it in their orbit. And it is the gravitational attraction of earth which makes the moon (or artificial satellite) go around the earth repeatedly.
Few Derived physical Quantities :
Work (measured in joules , = Force in the direction of motion X distance)
Power (Watts) = Work done / Time taken.
Energy is the ability to do work. It is a scalar quantity. (kinetic & Potential)
SI unit of energy ( 1 calorie = 4.18 joules).
Concept of Escape velocity: If an object like a rocket is to escape into the space, then it must be given a high velocity which an object should have in order to overcome the earth’s gravity and enter into space. This is called ‘Escape Velocity’.
The escape velocity for all the objects on earth is found to be 11.6 km/sec.
Note that escape velocity is independent of the mass of the object. It depends upon the mass of earth and its radius.
The escape velocity on moon is 1/5th of that of earth. (2.32 km/sec).
Heat , Temperature (measured in Celsius or Kelvin) and thermometer:
K = C + 273
F = (9/5)C + 32
Specific Heat: is the amount of heat which is required to raise the temperature of a unit mass of a substance by 1 degree Celsius. It is measured in joules per kilogram per degree Celsius.
3 types of thermometer:
a. Galileo’s Gas thermometer : used air as gas.
b. Laboratory : uses mercury. (Temperature range is -10’C to 110’C)
c. Clinical: uses mercury. (Temperature range is 35’C to 42’C). Normal human body temperature 37’C (98.6 F).
Latent Heat: It is the amount of heat absorbed by a unit mass of the substance to change its state without change of temperature.
a. Fusion (solid to liquid change)
b. Vapourisation (liquid to gas change)
Saturated Vapour Pressure: is the pressure of vapour above the liquid surface when the vapour is in dynamic equilibrium with the liquid. The saturated vapour pressure of a liquid increases with temperature.
Boiling point: where saturated vapour pressure = atmospheric pressure. Concluding that an increase in pressure on the surface of water raises its boiling point.
Periodic Motion: Note that time period depends neither on the mass/nature of the bob nor on the amplitude (maximum displacement from origin) of pendulum.
T=2π square root of (length of pendulum/g) Frequency = 1/T
Wave motion :
Electromagnetic waves: does not require medium to travel eg. Light.
Vs
Mechanical : require medium eg. Sound.
Transverse waves: particles vibrate at right angles to the direction in which wave is moving eg. Light
Vs
Longitudinal : particles vibrate parallel to the direction of wave eg. Sound.
Wavelength: distance between 2 nearest points in a wave which are in same phase of vibration or distance between 2 crusts.
Velocity of wave = frequency of wave X wavelength
Note that the speed of sound depends on nature of medium, temperature & humidity of air. Sound cannot be heard on the surface of the moon because there is no air on the moon to carry the sound waves.
Interference is the combination of two or more electromagnetic waveforms to form a resultant wave in which the displacement is either reinforced or cancelled.
Diffraction is the phenomenon where waves encounter an obstacle or a slit.
Light is faster than sound.
Hearing frequency of humans : 20Hz to 20,000 Hz. The sound waves having frequency higher than 20,000 are called Ultrasonic.
Structure of Atom: protons , neutrons and electrons.
Atomic number = no. of protons.
Mass number = no. of protons + no. of neutrons.
Note that 92 is the highest atomic number of an atom available in nature. It belongs to Uranium.
Isotopes : same atomic number but different mass number.
Radioactivity: The spontaneous & uncontrollable disintegration of certain heavy atoms with emission of alpha/ beta and gamma rays.
Uranium – 238 (naturally radioactive, not easily found). Its isotope, Uranium- 235 is abundant in nature. So, it is used to make Plutonium-239 . The process of changing one element into another is done by ‘transmutation’.
Nuclear Fission can be spontaneous , prompt or delayed.
Nuclear fusion is the source of sun’s energy. Hydrogen atoms fuse to make helium atom. Composition of sun light :
a. Ultra-Violet (shortest wavelength, produces fluorescence in certain substances, harmful to skin because of its ionizing effects)
b. VIBGYOR – visible spectrum
c. Infrared (longest wavelength, produces heat)
Note that : frequency is inversely proportional to wavelength.
Sources of Energy:
Solar Energy: Solar cells are made from semi-conductor – Silicon and germanium. In Solar furnaces, big concave reflectors are used to melt metals.
Tidal Energy has been used in India at 3 places:
a. Gulf of Kutch (Gujarat)
b. Gulf of Cambay (Gujarat)
c. Sunderbans along the east coast in west Bengal.
Biomass is converted into combustible gas constituting of methane, carbon dioxide, hydrogen and traces of hydrogen sulphide.
The slow conversion of wood into coal by a biochemical process extending over a million of years is called ‘carbonisation’.
Petroleum is a mixture of mainly butane , others being propane & ethane.
LPG is mixed with ‘mercaptan’ to enable detection of leaks.
Natural Gas consists of 95% methane, 5% ethane, 2% propane, .06% butane.
When natural gas is heated strongly in the absence of air, it decomposes. The hydrogen then obtained is used in the manufacture of ammonia & fertilizers.
And the carbon is used as a filler in carbon industry.
Note: calorific value of LPG (50 kj/g) < Natural gas (55 kj/g)
Refraction : When a ray of light is travelling from one medium to another, it changes direction.
a. Denser to lighter (away from normal)
b. Lighter to denser (towards the normal)
Law I : incident, refracted ray and normal lie in the same plane at point of incidence.
Law II or Snell’s Law : n1 sin (angle of incidence) = n2 sin(angel of refraction).
Lateral displacement : the perpendicular shift of the incident ray from the emergent ray. It increases with increase in thickness of glass and/or in the angle of incidence.
Reflection :
Law I : incident ray, reflected ray and normal all lie in the same plane.
Law II : angle of incidence= angle of reflection.
Lateral Inversion : the change of sides of an object and its mirror image.
Concave Mirrors used in torches, search light and vehicles, shaving mirrors.
Position of Object
Position of Image
Size of Image
Nature of Image
At infinity
At focus
Point-sized
Real & Inverted
Beyond C
Between F & C
Diminished
Real & Inverted
At C
At C
Same
Real & Inverted
Between C & F
Beyond C
Enlarged
Real & Inverted
At F
At infinity
Highly enlarged
Real & Inverted
Between P & F
Behind the mirror
Enlarged
Virtual and erect
Convex Mirrors used as rear view mirrors in automobiles. Diminished images.
Position of Object
Position of Image
Size of Image
Nature of Image
At infinity
At F, Behind mirror
Small Point
Virtual, erect
Between P & infinity
Between P & F, behind the mirror
Diminished
Virtual, erect
F=R/2
PRISM: Dispersion : the phenomenon due to which light splits into seven colours when passed through an equilateral prism.
Angle of (incidence + emergence) = angle of (prism +deviation)
Compound Microscope requires 2 convex lens with varying focal length for an enlarged view of object nearby. Objective lens is the one with lesser focal length.
Telescope requires 2 convex lens. Objective is of larger focal length here in order to obtain image of an object far far away.
Power of a lens (in dioptre) = 1/Focal length (in meters)
Lens formula 1/f = 1/v – 1/u
A photographic camera is based on the principle that if an object is placed beyond 2F of a convex lens, it always forms a real, diminished and inverted image between F and 2F on the other side of the lens. Eye functions similarily.
Magnetism : Magnetite is the only natural magnet known (its an iron ore Fe3O4). However, a mixture of ferric oxide and barium oxide called ‘ferrite’ is used in transistors and radio. Most powerful magnets are made from alloys of aluminium, nickel and cobalt (ALNICO).
Note that the geographic north pole of the earth lies in the magnetic south pole of earth.
Electric Cell is a device in which potential difference maintained between its two terminals by the conversion of chemical energy into electrical energy.
1. Voltaic cell – wet cell, 2 metallic plates (one of copper, other one Zinc). Each plate is provided with a brass terminal. Electrolyte is H2SO4.
2. Daniell Cell – can supply steady and continous current till its chemicals are not exhausted. One copper rod, other one also copper rod but perforated with copper sulphate crystals. There exists a porous pot containing Zinc sulphate or dilute sulphuric acid.
3. Dry Leclanche Cell – commonly used in transistors. It consists of zinc cylinders wrapped in a non-conducting material.
Note that Petrol, kerosene, diesel , asbestos, alcohol and benzene are non-conductors of electricity (also called insulators).
Electromagnetism : A coil with a core of iron nail acts as a magnet only when electric current flows around iron nail. This phenomenon is used in electric bells, fans, TV for deflecting electron beam on picture tube.
Electromagnetic Induction or Faraday’s experiment : When a magnetic field is changed near a conductor, an induced AC current is produced. The magnitude of the current depends on
a) Strength of magnet
b) Number of turns in coil.
c) Relative motion of magnet with respect to coil.
Accommodation of Eye : The process by which ciliary muscles alter the focal length of the crystalline lens, so as to focus the nearer or the far off objects clearly on the retina. For object at infinity , focal length of eye is 1.7 cm. For more downloads, visit www.studyiq.in
The pigment in the Iris decides the colour of the eye.
Iris adjusts the size of pupil to determine the amount of light entering eye.
Eye contains a crystalline lens (double convex).
Ciliary muscles are responsible for change in focal length of the eye.
The least distance of distinct vision is 25 cm. (maximum being infinity).
Defects in eye :
a. Hyperopia: far-sightedness, cannot see nearby objects clearly
b. Myopia: near-sightedness.
Instruments
Use
Altimeter
Measures altitudes (used in aircrafts)
Ammeter
electric current in a circuit
Animometer
power & velocity of wind
Audiometer
Intensity of sound
Barometer
Atmospheric pressure
Callipers
Inner and outer diameters of cylinders
Calorimeter
Quantity of heat
Dilatometer
Change in volume
Dynamometer
Electric power generated by engine
Electrometer
Small Potential differences in electric currents
Endoscope
Examines internal parts of body
Galvanometer
Measures sharpness of electric current
Hydrometer
Relative density of liquids
Hygrometer
Atmospheric humidity
Hypsometer
Determine boiling point of liquids
Lactometer
Relative density of milk, test purity
Micrometer
To obtain 1/100th of a millimetre
Microphone
Converts sound waves to electrical vibration
Microscope
Magnified view
Periscope
To view objects above sea level (used in submarines) uses reflection
Radar
Detect direction & range of aeroplane, uses radiowaves
Spectroscope
Record spectra
Stereoscope
To view 2D pictures
Teleprinter
Receive & send typed messages.
Telescope
To view Distant objects
Thermostat
Regulates temperature to a particular point
Voltmeter
Measures electric potential between two points
Important Inventions and Inventor
a) Aeroplane : Wright brothers.
b) Cinematograph & electric Lamp : Thomas Alva Edison
c) Theory of Evolution : Charles Darwin
d) Fountain Pen: L.E. Waterman.
e) Diesel engine : Rudolf Diesel
f) Radio : G Marconi
g) Radium : Marie & Pierre Curie
h) Steam Engine: Thomas Newcome
i) Jet Engine: Sir Frank Whittle.
j) Razor: K G Gillette.
k) Vulcanized Rubber: Charles Goodyear
l) Telephone : Alexander Graham Bell
m) TV : Johan Logie Bared
n) Transistor : Bardeen , Shockley
o) Typewriter : C Sholes
Discoveries & Scientists
a) Proton : Rutherford.
b) Neutron : James Chadwick
c) Atom : John Dalton
d) Atomic Structure : Neil Bohr & Rutherford.
e) Radioactivity : Henry Becquerel
f) X-Rays : Roentgen
g) Photoelectric Effect: Albert Einstein
h) Periodic Table : Mendeleev
i) Nuclear Reactor : Anrico Fermi
j) Dynamite : Alfred Nobel
Test your Understanding
PART I
Question 1: Light is a form of energy produced by a ______.
1.luminous object
2.transparent object
3.non-luminous object
4.opaque object
Question 2: An example for non-luminous object is ___________.
1.a candle
2.the sun
3.an electric bulb
4.the moon
Question 3: The image formed by a plane mirror is always _______.
1.real and erect
2.virtual and erect
3.real and inverted
4.virtual and inverted
Question 4: The focus of a concave mirror is ________.
1.Real
2.Virtual
3.Undefined
4.at the pole
Question 5: A converging mirror is known as ________.
1.convex mirror
2.plane mirror
3.concave mirror
4.cylindrical mirror
Question 6: An image formed by a convex mirror is always ________.
1.virtual, erect and diminished
2.virtual, real and magnified
3.real, inverted and diminished
4.real, erect and magnified
Question 7: If the image formed by a concave mirror is virtual, erect and magnified, then the object is placed __________.
1.between the pole of the mirror and the focus
2.beyond the centre of curvature
3.at the centre of curvature
4.at the focus
Question 8: Dentists use a _____________ to focus light on the tooth of a patient.
1.concave mirror
2.convex mirror
3.plane mirror
4.cylindrical mirror
Question 9: An object is placed 1.5 m from a plane mirror. How far is the image from the person?
1.
m
2.1.5 m
3.2 m
4.1 m
Question 10: Name the type of image that can be obtained on a screen.
1.Virtual
2.Real
3.Diverging
4.Converging
Question 11: Butter paper is an example for _______ object.
1.a transparent
2.a translucent
3.an opaque
4.a luminous
Question 12: If an incident ray passes through the centre of curvature of a spherical mirror, the reflected ray will __________________.
1.pass through the focus
2.pass through the centre of curvature
3.pass through the pole
4.retrace its path
Question 13: A positive magnification greater than unity indicate _____________________.
1.real image
2.virtual image
3.neither real not virtual image
4.distorted image
Question 14: The focal length of a lens whose power is -1.5 D is _______.
1.-66.66 cm
2.+ 1.5 m
3.+ 66.66 cm
4.-1.5 m
Question 15: A virtual image is formed by _______.
1.a slide projector in a cinema hall
2.the ordinary camera
3.a simple microscope
4.Telescope
Question 16: An object is placed 25 cm from a convex lens whose focal length is 10 cm. The image distance is ________ cm.
1.50 cm
2.16.66 cm
3.6.66 cm
4.10 cm
Question 17: A ray of light travels from a medium of refractive index n1 to a medium of refractive index n2. If angle of incidence is i and the angle of refraction is r. Then is equal to
1.n1
2.n2
3.n21
4.n12
Question 18: Two thin lenses of power +5 D and -2 D are placed in contact with each other. Focal length of the combination is
1.+3 m
2.-3 m
3.0.33 m
4.-0.33 m
Question 19: A long-sighted person cannot see objects nearer to his eye than 50 cm. To enable him to read a book 25 cm away, he should use spectacle lenses whose power in dioptres is ____.
1.-6
2.-4
3.-2
4.+ 4
Question 20: Hypermetropia is rectified by using
1.convex lens
2.concave lens
3.cylindrical lens
4.progressive lens
Question 21: When a wave travels through a medium ______.
1.particles are transferred from one place to another
2.energy is transferred in a periodic manner
3.energy is transferred at a constant speed
4.none of the above statements is applicable
Question 22: The minimum distance between the source and the reflector, so that an echo is heard is approximately equal to ______.
1.10 m
2.17 m
3.34 m
4.50 m
Question 23: Bats detect the obstacles in their path by receiving the reflected ______.
1.infrasonic waves
2.radio waves
3.electro-magnetic waves
4.ultrasonic waves
Question 24: The amplitude of a wave is ______.
1.the distance the wave moves in one second
2.the distance the wave moves in one time period of the wave
3.the maximum distance moved by the medium particles on either side of the mean position
4.the distance equal to one wave length
Question 25: The physical quantity, which oscillates in most waves, is
1.Mass
2.Energy
3.Amplitude
4.wavelength
Question 26: The speed of sound in medium depends upon
1.Amplitude
2.Frequency
3.wavelength
4.properties of the medium
Question 27: Which of the following will remain unchanged when a sound wave travels in air or in water?
1.Amplitude
2.Wavelength
3.Frequency
4.Speed
Question 28: A source of frequency of 500 Hz emits waves of wavelength 0.4 m, how long does the waves take to travel 600 m?
1.3 s
2.6 s
3.9 s
4.12 s
Question 29: Sound and light waves both
1.have similar wavelength
2.obey the laws of reflection
3.travel as longitudinal waves
4.travel through vacuum
Question 30: The method of detecting the presence, position and direction of motion of distant objects by reflecting a beam of sound waves is known as
1.RADAR
2.SONAR
3.MIR
4.CRO
Question 31: The technique used by bats to find their way or to locate food is _______.
1.SONAR
2.RADAR
3.Echolocation
4.Flapping
Question 32: An ultrasonic wave is sent from a ship towards the bottom of the sea. It is found that the time interval between the sending and receiving of the wave is 1.6 s. What is the depth of the sea, if the velocity of sound in the seawater is 1400 m/s?
1.1120 m
2.560 m
3.1400 m
4.112 m
Question 33: Unit of wavelength is __________.
1.Newton
2.Erg
3.Dyne
4.Angstrom
Question 34: The distance between a compression and the next rarefaction of a longitudinal wave is __________.
1.lamda/4
2.lamda/8
3.lamda/2
4.None of these
None of these
Question 35: The persistence of audible sound due to the successive reflections from the surrounding objects even after the source has stopped to produce that sound is called _________.
1.Reflection
2.Echo
3.Reverberation
4.Rarefaction
Question 36: A and B are two objects with masses 100 kg and 75 kg respectively, then ________ .
1.both will have the same inertia
2.B will have more inertia
3.A will have more inertia
4.both will have less inertia
Question 37: The sparks produced during sharpening of a knife against a grinding wheel leaves the rim of the wheel tangentially. This is due to ________
1.inertia of rest
2.inertia of motion
3.inertia of direction
4.force applied
Question 38: When a force of 1N acts on a mass of 1kg that is free to move, the object moves with
1.a speed of 1 m/s
2.a speed of 1 km/s
3.an acceleration 10 m/s2
4.an acceleration of 1 m/s2
Question 39: What is the force acting on an object of mass 10 kg moving with a uniform velocity of 10 m/s ?
1.100 N
2.10 N
3.0
4.1 N
Question 40: An athlete can take a longer jump if he comes running from a distance as compared to that when he jumps suddenly. Identify the type of inertia.
1.Inertia of rest
2.Inertia of motion
3.Inertia of direction
4.Inertia of position
Question 41: Impulse = _________.
1.ma
2.Ft
3.mv
4.(v-u)/t
Question 42: The resultant of action and reaction forces is _______.
1.greater than zero
2.less than zero
3.Zero
4.none of the above
Question 43: A coolie carries a load of 500 N to a distance of 100 m. The work done by him is
1.5 N
2.50,000 Nm
3.0
4.1/5 N
Question 44: The P.E. of a body at a certain height is 200 J. The kinetic energy possessed by it when it just touches the surface of the earth is
1.> P.E.
2.< P.E.
3.= P.E.
4.cannot be known
Question 45: Two objects of masses 1 x 10-3 kg and 4 x 10-3 kg have equal momentum. What is the ratio of their kinetic energies?
1.4:1
2.2:1
3.16:1
4.Question 46: The type of energy possessed by a simple pendulum, when it is at the mean position is
1.kinetic energy
2.potential energy
3.potential energy + kinetic energy
4.sound energy
Question 47: An iron sphere of mass 30 kg has the same diameter as an aluminium sphere whose mass is 10.5 kg. The spheres are dropped simultaneously from a cliff. When they are 10 m from the ground, they have the same _______.
1.acceleration
2.momentum
3.potential energy
4.kinetic energy
Question 48: Which of the following statements does not represent ohm's law?
1.current / potential difference = constant
2.potential difference / current = constant
3.potential difference = current x resistance
4.current = resistance x potential difference
Question 49: Two resistances of 100 W and zero ohm are connected in parallel. The overall resistance will be
1.100 W
2.50 W
3.25 W
4.zero ohm
Question 50: Three resistors 2 W , 3 W and 4 W are connected so that the equivalent resistance is 9 W . The resistors are connected _________.
1.all in series
2.all in parallel
3.2 W and 3 W in parallel and the combination in series with 4 W
4.2 W and 3 W in series and the combination in parallel to 4 W
ANSWER KEY TO PART I
Ans 1).1 Ans 2 6)4
Ans 2)4 Ans 27)3
Ans 3) 2 Ans 28) 1
Ans 4) 2 Ans 29)2
Ans 5)1 Ans 30)2
Ans 6)1 Ans 31)3
Ans 7)1 Ans 32)1
Ans 8)1 Ans 33)4
Ans 9)1 Ans 34)3
Ans 10)2 Ans 35)3
Ans 11)2 Ans 36)3
Ans 12)4 Ans 37)3
Ans 13)2 Ans 38)4
Ans 14)1 Ans 39)3
Ans 15)3 Ans 40)2
Ans 16)2 Ans 41)2
Ans 17)3 Ans 42)1
Ans 18)3 Ans 43)3
Ans 19)4 Ans 44)1
Ans 20)1 Ans 45)1
Ans 21)3 Ans 46)1
Ans 22)2 Ans 47)1
Ans 23)4 Ans 48)4
Ans 24)3 Ans 49)1
Ans 25)3 Ans 50)1
Scalar: Those have only magnitude eg. Distance ( measured in metre), time(sec), current (ampere), temperature (Kelvin), luminous intensity (candela), mass (kg), amount of substance (mole).
Vector quantities: Those which have direction and magnitude eg.
1. Displacement vs Distance
Distance is the actual length of path travelled by a moving body.
Displacement is the shortest distance the initial and final position of the body, along with the direction.
Distance travelled by you to reach study iq = 3+4+7= 14 units but displacement is the length of the dotted line joining your home and institute directing towards south-east.
2. Velocity: defines Speed along with direction of motion of body.
3. Acceleration : rate of change of velocity with respect to time.
Newton’s Laws of Motion:
I. A body at rest will remain at rest and a body in motion will continue to remain in motion until an external force is applied to it.
Concept of Inertia : A body resist change in its state of rest or of uniform motion.
a. Inertia of Rest
b. Inertia of Motion.
c. Inertia of Direction.
II. F (measured in newton) = m X a
Or
We can say, Force applied to a body is directly proportional to the rate of change of momentum (momentum = mass X velocity) which is produced by body.
III. Every action has an equal and opposite reaction. That means When two bodies act upon one another, their total momentum remains constant provided no external force is applied to it.
Concept of friction :
Some force acting on a stationary object which opposes its motion. This is Friction. Its of 3 types:
a. Static friction : exerted by object at rest
b. Sliding (also called Dynamic or Kinetic friction): exerted when object slides over a surface.
c. Rolling: exerted when an object rolls over a surface.
Static > Sliding > Rolling
Circular motion: When a body moves around a fixed point in a circular path with uniform speed.
Note that circular motion is accelerated even though the speed of body remains constant.
Projectile motion: A falling object having a horizontal velocity is called a projectile, and it moves in a curved path called parabola. It Possesses :
A horizontal motion with constant velocity.
A vertical motion with constant acceleration.
Note that: it is the gravitational attraction of the sun which keeps the planets revolving around it in their orbit. And it is the gravitational attraction of earth which makes the moon (or artificial satellite) go around the earth repeatedly.
Few Derived physical Quantities :
Work (measured in joules , = Force in the direction of motion X distance)
Power (Watts) = Work done / Time taken.
Energy is the ability to do work. It is a scalar quantity. (kinetic & Potential)
SI unit of energy ( 1 calorie = 4.18 joules).
Concept of Escape velocity: If an object like a rocket is to escape into the space, then it must be given a high velocity which an object should have in order to overcome the earth’s gravity and enter into space. This is called ‘Escape Velocity’.
The escape velocity for all the objects on earth is found to be 11.6 km/sec.
Note that escape velocity is independent of the mass of the object. It depends upon the mass of earth and its radius.
The escape velocity on moon is 1/5th of that of earth. (2.32 km/sec).
Heat , Temperature (measured in Celsius or Kelvin) and thermometer:
K = C + 273
F = (9/5)C + 32
Specific Heat: is the amount of heat which is required to raise the temperature of a unit mass of a substance by 1 degree Celsius. It is measured in joules per kilogram per degree Celsius.
3 types of thermometer:
a. Galileo’s Gas thermometer : used air as gas.
b. Laboratory : uses mercury. (Temperature range is -10’C to 110’C)
c. Clinical: uses mercury. (Temperature range is 35’C to 42’C). Normal human body temperature 37’C (98.6 F).
Latent Heat: It is the amount of heat absorbed by a unit mass of the substance to change its state without change of temperature.
a. Fusion (solid to liquid change)
b. Vapourisation (liquid to gas change)
Saturated Vapour Pressure: is the pressure of vapour above the liquid surface when the vapour is in dynamic equilibrium with the liquid. The saturated vapour pressure of a liquid increases with temperature.
Boiling point: where saturated vapour pressure = atmospheric pressure. Concluding that an increase in pressure on the surface of water raises its boiling point.
Periodic Motion: Note that time period depends neither on the mass/nature of the bob nor on the amplitude (maximum displacement from origin) of pendulum.
T=2π square root of (length of pendulum/g) Frequency = 1/T
Wave motion :
Electromagnetic waves: does not require medium to travel eg. Light.
Vs
Mechanical : require medium eg. Sound.
Transverse waves: particles vibrate at right angles to the direction in which wave is moving eg. Light
Vs
Longitudinal : particles vibrate parallel to the direction of wave eg. Sound.
Wavelength: distance between 2 nearest points in a wave which are in same phase of vibration or distance between 2 crusts.
Velocity of wave = frequency of wave X wavelength
Note that the speed of sound depends on nature of medium, temperature & humidity of air. Sound cannot be heard on the surface of the moon because there is no air on the moon to carry the sound waves.
Interference is the combination of two or more electromagnetic waveforms to form a resultant wave in which the displacement is either reinforced or cancelled.
Diffraction is the phenomenon where waves encounter an obstacle or a slit.
Light is faster than sound.
Hearing frequency of humans : 20Hz to 20,000 Hz. The sound waves having frequency higher than 20,000 are called Ultrasonic.
Structure of Atom: protons , neutrons and electrons.
Atomic number = no. of protons.
Mass number = no. of protons + no. of neutrons.
Note that 92 is the highest atomic number of an atom available in nature. It belongs to Uranium.
Isotopes : same atomic number but different mass number.
Radioactivity: The spontaneous & uncontrollable disintegration of certain heavy atoms with emission of alpha/ beta and gamma rays.
Uranium – 238 (naturally radioactive, not easily found). Its isotope, Uranium- 235 is abundant in nature. So, it is used to make Plutonium-239 . The process of changing one element into another is done by ‘transmutation’.
Nuclear Fission can be spontaneous , prompt or delayed.
Nuclear fusion is the source of sun’s energy. Hydrogen atoms fuse to make helium atom. Composition of sun light :
a. Ultra-Violet (shortest wavelength, produces fluorescence in certain substances, harmful to skin because of its ionizing effects)
b. VIBGYOR – visible spectrum
c. Infrared (longest wavelength, produces heat)
Note that : frequency is inversely proportional to wavelength.
Sources of Energy:
Solar Energy: Solar cells are made from semi-conductor – Silicon and germanium. In Solar furnaces, big concave reflectors are used to melt metals.
Tidal Energy has been used in India at 3 places:
a. Gulf of Kutch (Gujarat)
b. Gulf of Cambay (Gujarat)
c. Sunderbans along the east coast in west Bengal.
Biomass is converted into combustible gas constituting of methane, carbon dioxide, hydrogen and traces of hydrogen sulphide.
The slow conversion of wood into coal by a biochemical process extending over a million of years is called ‘carbonisation’.
Petroleum is a mixture of mainly butane , others being propane & ethane.
LPG is mixed with ‘mercaptan’ to enable detection of leaks.
Natural Gas consists of 95% methane, 5% ethane, 2% propane, .06% butane.
When natural gas is heated strongly in the absence of air, it decomposes. The hydrogen then obtained is used in the manufacture of ammonia & fertilizers.
And the carbon is used as a filler in carbon industry.
Note: calorific value of LPG (50 kj/g) < Natural gas (55 kj/g)
Refraction : When a ray of light is travelling from one medium to another, it changes direction.
a. Denser to lighter (away from normal)
b. Lighter to denser (towards the normal)
Law I : incident, refracted ray and normal lie in the same plane at point of incidence.
Law II or Snell’s Law : n1 sin (angle of incidence) = n2 sin(angel of refraction).
Lateral displacement : the perpendicular shift of the incident ray from the emergent ray. It increases with increase in thickness of glass and/or in the angle of incidence.
Reflection :
Law I : incident ray, reflected ray and normal all lie in the same plane.
Law II : angle of incidence= angle of reflection.
Lateral Inversion : the change of sides of an object and its mirror image.
Concave Mirrors used in torches, search light and vehicles, shaving mirrors.
Position of Object
Position of Image
Size of Image
Nature of Image
At infinity
At focus
Point-sized
Real & Inverted
Beyond C
Between F & C
Diminished
Real & Inverted
At C
At C
Same
Real & Inverted
Between C & F
Beyond C
Enlarged
Real & Inverted
At F
At infinity
Highly enlarged
Real & Inverted
Between P & F
Behind the mirror
Enlarged
Virtual and erect
Convex Mirrors used as rear view mirrors in automobiles. Diminished images.
Position of Object
Position of Image
Size of Image
Nature of Image
At infinity
At F, Behind mirror
Small Point
Virtual, erect
Between P & infinity
Between P & F, behind the mirror
Diminished
Virtual, erect
F=R/2
PRISM: Dispersion : the phenomenon due to which light splits into seven colours when passed through an equilateral prism.
Angle of (incidence + emergence) = angle of (prism +deviation)
Compound Microscope requires 2 convex lens with varying focal length for an enlarged view of object nearby. Objective lens is the one with lesser focal length.
Telescope requires 2 convex lens. Objective is of larger focal length here in order to obtain image of an object far far away.
Power of a lens (in dioptre) = 1/Focal length (in meters)
Lens formula 1/f = 1/v – 1/u
A photographic camera is based on the principle that if an object is placed beyond 2F of a convex lens, it always forms a real, diminished and inverted image between F and 2F on the other side of the lens. Eye functions similarily.
Magnetism : Magnetite is the only natural magnet known (its an iron ore Fe3O4). However, a mixture of ferric oxide and barium oxide called ‘ferrite’ is used in transistors and radio. Most powerful magnets are made from alloys of aluminium, nickel and cobalt (ALNICO).
Note that the geographic north pole of the earth lies in the magnetic south pole of earth.
Electric Cell is a device in which potential difference maintained between its two terminals by the conversion of chemical energy into electrical energy.
1. Voltaic cell – wet cell, 2 metallic plates (one of copper, other one Zinc). Each plate is provided with a brass terminal. Electrolyte is H2SO4.
2. Daniell Cell – can supply steady and continous current till its chemicals are not exhausted. One copper rod, other one also copper rod but perforated with copper sulphate crystals. There exists a porous pot containing Zinc sulphate or dilute sulphuric acid.
3. Dry Leclanche Cell – commonly used in transistors. It consists of zinc cylinders wrapped in a non-conducting material.
Note that Petrol, kerosene, diesel , asbestos, alcohol and benzene are non-conductors of electricity (also called insulators).
Electromagnetism : A coil with a core of iron nail acts as a magnet only when electric current flows around iron nail. This phenomenon is used in electric bells, fans, TV for deflecting electron beam on picture tube.
Electromagnetic Induction or Faraday’s experiment : When a magnetic field is changed near a conductor, an induced AC current is produced. The magnitude of the current depends on
a) Strength of magnet
b) Number of turns in coil.
c) Relative motion of magnet with respect to coil.
Accommodation of Eye : The process by which ciliary muscles alter the focal length of the crystalline lens, so as to focus the nearer or the far off objects clearly on the retina. For object at infinity , focal length of eye is 1.7 cm. For more downloads, visit www.studyiq.in
The pigment in the Iris decides the colour of the eye.
Iris adjusts the size of pupil to determine the amount of light entering eye.
Eye contains a crystalline lens (double convex).
Ciliary muscles are responsible for change in focal length of the eye.
The least distance of distinct vision is 25 cm. (maximum being infinity).
Defects in eye :
a. Hyperopia: far-sightedness, cannot see nearby objects clearly
b. Myopia: near-sightedness.
Instruments
Use
Altimeter
Measures altitudes (used in aircrafts)
Ammeter
electric current in a circuit
Animometer
power & velocity of wind
Audiometer
Intensity of sound
Barometer
Atmospheric pressure
Callipers
Inner and outer diameters of cylinders
Calorimeter
Quantity of heat
Dilatometer
Change in volume
Dynamometer
Electric power generated by engine
Electrometer
Small Potential differences in electric currents
Endoscope
Examines internal parts of body
Galvanometer
Measures sharpness of electric current
Hydrometer
Relative density of liquids
Hygrometer
Atmospheric humidity
Hypsometer
Determine boiling point of liquids
Lactometer
Relative density of milk, test purity
Micrometer
To obtain 1/100th of a millimetre
Microphone
Converts sound waves to electrical vibration
Microscope
Magnified view
Periscope
To view objects above sea level (used in submarines) uses reflection
Radar
Detect direction & range of aeroplane, uses radiowaves
Spectroscope
Record spectra
Stereoscope
To view 2D pictures
Teleprinter
Receive & send typed messages.
Telescope
To view Distant objects
Thermostat
Regulates temperature to a particular point
Voltmeter
Measures electric potential between two points
Important Inventions and Inventor
a) Aeroplane : Wright brothers.
b) Cinematograph & electric Lamp : Thomas Alva Edison
c) Theory of Evolution : Charles Darwin
d) Fountain Pen: L.E. Waterman.
e) Diesel engine : Rudolf Diesel
f) Radio : G Marconi
g) Radium : Marie & Pierre Curie
h) Steam Engine: Thomas Newcome
i) Jet Engine: Sir Frank Whittle.
j) Razor: K G Gillette.
k) Vulcanized Rubber: Charles Goodyear
l) Telephone : Alexander Graham Bell
m) TV : Johan Logie Bared
n) Transistor : Bardeen , Shockley
o) Typewriter : C Sholes
Discoveries & Scientists
a) Proton : Rutherford.
b) Neutron : James Chadwick
c) Atom : John Dalton
d) Atomic Structure : Neil Bohr & Rutherford.
e) Radioactivity : Henry Becquerel
f) X-Rays : Roentgen
g) Photoelectric Effect: Albert Einstein
h) Periodic Table : Mendeleev
i) Nuclear Reactor : Anrico Fermi
j) Dynamite : Alfred Nobel
Test your Understanding
PART I
Question 1: Light is a form of energy produced by a ______.
1.luminous object
2.transparent object
3.non-luminous object
4.opaque object
Question 2: An example for non-luminous object is ___________.
1.a candle
2.the sun
3.an electric bulb
4.the moon
Question 3: The image formed by a plane mirror is always _______.
1.real and erect
2.virtual and erect
3.real and inverted
4.virtual and inverted
Question 4: The focus of a concave mirror is ________.
1.Real
2.Virtual
3.Undefined
4.at the pole
Question 5: A converging mirror is known as ________.
1.convex mirror
2.plane mirror
3.concave mirror
4.cylindrical mirror
Question 6: An image formed by a convex mirror is always ________.
1.virtual, erect and diminished
2.virtual, real and magnified
3.real, inverted and diminished
4.real, erect and magnified
Question 7: If the image formed by a concave mirror is virtual, erect and magnified, then the object is placed __________.
1.between the pole of the mirror and the focus
2.beyond the centre of curvature
3.at the centre of curvature
4.at the focus
Question 8: Dentists use a _____________ to focus light on the tooth of a patient.
1.concave mirror
2.convex mirror
3.plane mirror
4.cylindrical mirror
Question 9: An object is placed 1.5 m from a plane mirror. How far is the image from the person?
1.
m
2.1.5 m
3.2 m
4.1 m
Question 10: Name the type of image that can be obtained on a screen.
1.Virtual
2.Real
3.Diverging
4.Converging
Question 11: Butter paper is an example for _______ object.
1.a transparent
2.a translucent
3.an opaque
4.a luminous
Question 12: If an incident ray passes through the centre of curvature of a spherical mirror, the reflected ray will __________________.
1.pass through the focus
2.pass through the centre of curvature
3.pass through the pole
4.retrace its path
Question 13: A positive magnification greater than unity indicate _____________________.
1.real image
2.virtual image
3.neither real not virtual image
4.distorted image
Question 14: The focal length of a lens whose power is -1.5 D is _______.
1.-66.66 cm
2.+ 1.5 m
3.+ 66.66 cm
4.-1.5 m
Question 15: A virtual image is formed by _______.
1.a slide projector in a cinema hall
2.the ordinary camera
3.a simple microscope
4.Telescope
Question 16: An object is placed 25 cm from a convex lens whose focal length is 10 cm. The image distance is ________ cm.
1.50 cm
2.16.66 cm
3.6.66 cm
4.10 cm
Question 17: A ray of light travels from a medium of refractive index n1 to a medium of refractive index n2. If angle of incidence is i and the angle of refraction is r. Then is equal to
1.n1
2.n2
3.n21
4.n12
Question 18: Two thin lenses of power +5 D and -2 D are placed in contact with each other. Focal length of the combination is
1.+3 m
2.-3 m
3.0.33 m
4.-0.33 m
Question 19: A long-sighted person cannot see objects nearer to his eye than 50 cm. To enable him to read a book 25 cm away, he should use spectacle lenses whose power in dioptres is ____.
1.-6
2.-4
3.-2
4.+ 4
Question 20: Hypermetropia is rectified by using
1.convex lens
2.concave lens
3.cylindrical lens
4.progressive lens
Question 21: When a wave travels through a medium ______.
1.particles are transferred from one place to another
2.energy is transferred in a periodic manner
3.energy is transferred at a constant speed
4.none of the above statements is applicable
Question 22: The minimum distance between the source and the reflector, so that an echo is heard is approximately equal to ______.
1.10 m
2.17 m
3.34 m
4.50 m
Question 23: Bats detect the obstacles in their path by receiving the reflected ______.
1.infrasonic waves
2.radio waves
3.electro-magnetic waves
4.ultrasonic waves
Question 24: The amplitude of a wave is ______.
1.the distance the wave moves in one second
2.the distance the wave moves in one time period of the wave
3.the maximum distance moved by the medium particles on either side of the mean position
4.the distance equal to one wave length
Question 25: The physical quantity, which oscillates in most waves, is
1.Mass
2.Energy
3.Amplitude
4.wavelength
Question 26: The speed of sound in medium depends upon
1.Amplitude
2.Frequency
3.wavelength
4.properties of the medium
Question 27: Which of the following will remain unchanged when a sound wave travels in air or in water?
1.Amplitude
2.Wavelength
3.Frequency
4.Speed
Question 28: A source of frequency of 500 Hz emits waves of wavelength 0.4 m, how long does the waves take to travel 600 m?
1.3 s
2.6 s
3.9 s
4.12 s
Question 29: Sound and light waves both
1.have similar wavelength
2.obey the laws of reflection
3.travel as longitudinal waves
4.travel through vacuum
Question 30: The method of detecting the presence, position and direction of motion of distant objects by reflecting a beam of sound waves is known as
1.RADAR
2.SONAR
3.MIR
4.CRO
Question 31: The technique used by bats to find their way or to locate food is _______.
1.SONAR
2.RADAR
3.Echolocation
4.Flapping
Question 32: An ultrasonic wave is sent from a ship towards the bottom of the sea. It is found that the time interval between the sending and receiving of the wave is 1.6 s. What is the depth of the sea, if the velocity of sound in the seawater is 1400 m/s?
1.1120 m
2.560 m
3.1400 m
4.112 m
Question 33: Unit of wavelength is __________.
1.Newton
2.Erg
3.Dyne
4.Angstrom
Question 34: The distance between a compression and the next rarefaction of a longitudinal wave is __________.
1.lamda/4
2.lamda/8
3.lamda/2
4.None of these
None of these
Question 35: The persistence of audible sound due to the successive reflections from the surrounding objects even after the source has stopped to produce that sound is called _________.
1.Reflection
2.Echo
3.Reverberation
4.Rarefaction
Question 36: A and B are two objects with masses 100 kg and 75 kg respectively, then ________ .
1.both will have the same inertia
2.B will have more inertia
3.A will have more inertia
4.both will have less inertia
Question 37: The sparks produced during sharpening of a knife against a grinding wheel leaves the rim of the wheel tangentially. This is due to ________
1.inertia of rest
2.inertia of motion
3.inertia of direction
4.force applied
Question 38: When a force of 1N acts on a mass of 1kg that is free to move, the object moves with
1.a speed of 1 m/s
2.a speed of 1 km/s
3.an acceleration 10 m/s2
4.an acceleration of 1 m/s2
Question 39: What is the force acting on an object of mass 10 kg moving with a uniform velocity of 10 m/s ?
1.100 N
2.10 N
3.0
4.1 N
Question 40: An athlete can take a longer jump if he comes running from a distance as compared to that when he jumps suddenly. Identify the type of inertia.
1.Inertia of rest
2.Inertia of motion
3.Inertia of direction
4.Inertia of position
Question 41: Impulse = _________.
1.ma
2.Ft
3.mv
4.(v-u)/t
Question 42: The resultant of action and reaction forces is _______.
1.greater than zero
2.less than zero
3.Zero
4.none of the above
Question 43: A coolie carries a load of 500 N to a distance of 100 m. The work done by him is
1.5 N
2.50,000 Nm
3.0
4.1/5 N
Question 44: The P.E. of a body at a certain height is 200 J. The kinetic energy possessed by it when it just touches the surface of the earth is
1.> P.E.
2.< P.E.
3.= P.E.
4.cannot be known
Question 45: Two objects of masses 1 x 10-3 kg and 4 x 10-3 kg have equal momentum. What is the ratio of their kinetic energies?
1.4:1
2.2:1
3.16:1
4.Question 46: The type of energy possessed by a simple pendulum, when it is at the mean position is
1.kinetic energy
2.potential energy
3.potential energy + kinetic energy
4.sound energy
Question 47: An iron sphere of mass 30 kg has the same diameter as an aluminium sphere whose mass is 10.5 kg. The spheres are dropped simultaneously from a cliff. When they are 10 m from the ground, they have the same _______.
1.acceleration
2.momentum
3.potential energy
4.kinetic energy
Question 48: Which of the following statements does not represent ohm's law?
1.current / potential difference = constant
2.potential difference / current = constant
3.potential difference = current x resistance
4.current = resistance x potential difference
Question 49: Two resistances of 100 W and zero ohm are connected in parallel. The overall resistance will be
1.100 W
2.50 W
3.25 W
4.zero ohm
Question 50: Three resistors 2 W , 3 W and 4 W are connected so that the equivalent resistance is 9 W . The resistors are connected _________.
1.all in series
2.all in parallel
3.2 W and 3 W in parallel and the combination in series with 4 W
4.2 W and 3 W in series and the combination in parallel to 4 W
ANSWER KEY TO PART I
Ans 1).1 Ans 2 6)4
Ans 2)4 Ans 27)3
Ans 3) 2 Ans 28) 1
Ans 4) 2 Ans 29)2
Ans 5)1 Ans 30)2
Ans 6)1 Ans 31)3
Ans 7)1 Ans 32)1
Ans 8)1 Ans 33)4
Ans 9)1 Ans 34)3
Ans 10)2 Ans 35)3
Ans 11)2 Ans 36)3
Ans 12)4 Ans 37)3
Ans 13)2 Ans 38)4
Ans 14)1 Ans 39)3
Ans 15)3 Ans 40)2
Ans 16)2 Ans 41)2
Ans 17)3 Ans 42)1
Ans 18)3 Ans 43)3
Ans 19)4 Ans 44)1
Ans 20)1 Ans 45)1
Ans 21)3 Ans 46)1
Ans 22)2 Ans 47)1
Ans 23)4 Ans 48)4
Ans 24)3 Ans 49)1
Ans 25)3 Ans 50)1
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