# Physics GS Objective Questions- A Must Have in Your Arsenal for Competitive Exams

Updated December 21, 2022

Physics GS Objective Questions featured on this page is result of sincere efforts put in by the team Career101.in. These questions are from length and breadth of Physics GS and they test your actual acumen which is very much required in making through the Government Jobs. In terms of assessment standards the objective questions asked from Physics GS can at times intriguing and you may not find at ease solving them. So, in its endevour to support your preparation for competitive exams, the compilation made by the team has put in hours quality time in matching the standard. The team hopes the collection below comes in really handy when you need it most.

### 1. What is the average power consumption of a heartbeat in an adult?

[A] 1.2 watt

[B] 112.5 watt

[C] 200 watt

[D] 500 watt

Explanation: Average power consumption by an adult in some of the common processes/activities: 1. Heartbeat – 1.2 watt, 2. Sleeping – 75 watt, 3. Slow walking – 200 watt, 4. Bicycling – 500 watt.

### 2. The work done by a variable force is given by:

[A] area under the force curve and the displacement axis

[B] square of the area under the force curve and the displacement axis

[C] natural log of the area under the force curve and the displacement axis

[D] twice the area under the force curve and the displacement axis

Correct Answer: [area under the force curve and the displacement axis]

Explanation: The work done by a variable force is given by the area under the force curve and the displacement axis. W = Area ABCDA

### 3. 1 killogram force produces how much acceleration in a body of mass 1 kg?

[A] 1 ms-2

[B] 0

[C] 9.8 ms-2

[D] -1 ms-2

Explanation: 1 Kilogram force or 1 Kilogram weight is that much force which produces an acceleration of 9.8 ms-2 in a body of mass 1 kg. Also, 1 kg wt. or 1 kg f = 9.8 N

### 4. The centripetal force and centrifugal force are ______:

[A] equal in magnitude and have same direction

[B] unequal in magnitude and have same direction

[C] equal in magnitude and have opposite direction

[D] unequal in magnitude and have opposite direction

Correct Answer: [equal in magnitude and have opposite direction]

Explanation: The centripetal force and centrifugal force are equal in magnitude and have opposite direction. Centrifugal force can be regarded as the reaction of centripetal force.

### 5. The value of coefficient of limiting friction does not depend on which of the following?

[A] nature of the surfaces in contact

[B] total area of the surfaces in contact

[C] material of the surfaces in contact

[D] All of the above

Correct Answer: [total area of the surfaces in contact]

Explanation: The coefficient of static friction can be defined as the ratio of the limiting static friction and the normal reaction between the 2 surfaces. The value of coefficient of limiting friction depends: 1. Nature of the surfaces in contact. 2. Material of the surfaces in contact.

### 6. The force acting on a body for a short time are called as:

[A] Average force

[B] Momentum

[C] Impulse

[D] Tension

Explanation: The force acting on a body for a short time are called as Impulse. Example: hitting a ball with a bat. Impulse = average force x time It is a measure of total effect of the force. Its unit is Ns.

### 7. Which of the following statements regarding vectors is not correct?

[A] A unit vector is dimensionless

[B] A vector cannot be divided by a vector

[C] A vector changes, when it is displaced to itself

[D] Current is not a vector quantity

Correct Answer: [A vector changes, when it is displaced to itself]

Explanation: A unit vector is unit less and dimensionless. A vector cannot be divided by a vector as a vector cannot be divided by a direction. A vector does not change, when it is displaced to itself. Time, Pressure, Surface Tension, Current are some of the quantities that have direction but are not vectors. A physical quantity is a vector only when it follows commutative law of addition of vectors.

### 8. What is the relation between Time period and Frequency in case of uniform circular motion?

[A] reciprocal to each other

[B] equal to each other

[C] no relation between them

[D] Time period is one half of the Frequency

Correct Answer: [reciprocal to each other]

Explanation: Time period and Frequency are reciprocal to each other in case of uniform circular motion. Time period = 1 /Frequency Time Period is the time taken by the object to complete one revolution. Frequency is the number of revolutions completed by the object in unit time.

### 9. What is the work done by centripetal force in case of Uniform Circular Motion?

[A] 1 joule

[B] 0 joule

[C] Depends on the magnitude of Force

[D] None of the above

Explanation: The work done by Centripetal Force in case of Uniform Circular Motion is zero. The displacement and force are mutually perpendicular to each other in case of centripetal force. Therefore, the work done is zero.

### 10. A projectile will achieve maximum horizontal range at which angle?

[A] 90°

[B] 60°

[C] 45°

[D] 30°

Explanation: A projectile will achieve maximum horizontal range when it is projected at an angle of 45°. This concept of maximum horizontal range is used by athletes in long jump, javelin throw and throwing cricket ball etc.

### 11. Which of the following physical quantities has no units?

[A] Reynold Number

[B] Rydberg constant

[C] Wave number

[D] Hubble constant

Explanation: Reynold Number has no units. The Reynolds number is the ratio of inertial forces to viscous forces. It is used for predicting if a flow condition will be laminar or turbulent.

### 12. Which of the following is correct about the properties of Gravitational Forces?

[A] They are the strongest forces in nature

[B] They observe inverse square law

[C] Both a and b

[D] None

Correct Answer: [They observe inverse square law]

Explanation: Gravitational Forces are the weakest forces in nature. They obey inverse square law as they vary inversely as the square of the distance between the two bodies. They are central forces and conservative forces. They operate over very long distances having an infinite range.

### 13. The recoiling of gun is an example of which of the following?

[A] Law of Conservation of Angular Momentum

[B] Law of Conservation of Linear Momentum

[C] Conversion of Kinetic Energy to Potential Energy

[D] Law of Conservation of Energy

Correct Answer: [Law of Conservation of Linear Momentum]

Explanation: The recoiling of gun is an example of Law of Conservation of Linear Momentum. When gun fires a bullet, it experiences a force in forward direction (action), as a result the gun exerts a backward force (reaction) on the shoulder. Thus, it is in accordance with Law of Conservation of Linear Momentum which is also the Newton’s 3rd law of motion.

### 14. Who among the following discovered X-rays?

[A] Marie Curie

[B] J.J Thomson

[C] W.C Roentgen

Explanation: X-rays were discovered by Wilhelm Conrad Roentgen. W.C Roengten discovered X-Rays while actually working on Cathode rays. X-rays is a form of electromagnetic radiation having a wavelength ranging from 0.01 to 10 nanometers and frequencies in the range 30 petahertz to 30 exahertz. Some Uses of X-Rays: The main use of X-rays is in medicine to check for a broken bone inside body. X-rays can also be used to kill cancer cells. X-rays are used at security checks at airports, railway stations etc. to check customers and baggage. X-rays are also used art historians to see if a picture has been painted on top of an older one. X-ray diffraction is also very important in spectroscopy and as a basis for X-ray crystallography.

### 15. An Electric generator is based on which of the following scientific principles?

[A] Faraday’s law of Electromagnetic Induction

[B] Super Conductivity

[C] Laws of Thermodynamics

[D] Newton’s Law of Motion

Explanation: An Electric generator works on the principle of Faraday’s law of Electromagnetic Induction. An electric generator uses mechanical energy to generate electricity applying Faraday’s law of induction. It spins a coil at a constant rate in a magnetic field to induce an oscillating emf.

### 16. Who among the following is credited for the Corpuscular theory of light?

[A] Isaac Newton

[B] Christiaan Huygens

[C] Albert Einstein

[D] James Clerk Maxwell

Explanation: The Corpuscular theory of light was given by Isaac Newton. It was replaced by Huygens’s wave theory when it failed to adequately explain the diffraction, interference and polarization of light. The Huygens’s wave theory was replaced by Planck s quantum theory and finally de-Broglie’s Dual-Theory of light replaced all previous ones.

### 17. Who among the following is credited to work for the unification of electricity, magnetism and optics field of Physics?

[A] James Clerk Maxwell

[C] Haris Christian Oersted

[D] Isaac Newton

Explanation: James Clerk Maxwell made the efforts for the unification of electricity, magnetism and optics field of Physics. He showed that light is an electromagnetic wave. James Clerk Maxwell was a Scottish mathematician, physicist and is known best for his mathematical work on electromagnetism and on the behaviour of gases.

### 18. Who gave the Theory of Relativity?

[A] Isaac Newton

[B] Archimedes

[C] Albert Einstein

[D] Galileo Galilei

Explanation: Albert Einstein was the founder of Theory of Relativity. According to Einstein’s theory, mass m is equivalent to energy E given by the relation E = mc^2 where c is speed of light in vacuum. Albert Einstein was awarded the 1921 Nobel Prize in Physics for his contribution to the field of Theoretical Physics.

### 19. Ohm is a unit of measuring _________?

[A] Resistance

[B] Voltage

[C] Current

[D] None of the above

[A] Dimensions

[B] Time

[C] Sound

[D] Temperature

### 21. What is the coefficient of restitution for a perfectly elastic collision?

[A] 0

[B] 1

[C] -1

[D] 100

Explanation: For a perfectly elastic collision, the coefficient of restitution is equal to 1 as the velocity of separation after collision is equal to the velocity of approach before collision. For a perfectly inelastic collision, the coefficient of restitution is equal to 0 as the velocity of separation after collision is equal to 0. The coefficient of restitution or coefficient of resilience is the ratio of relative velocity of separation after collision and the velocity of approach before collision.

### 22. Which of the following is true about universal gravitational constant in the case of two bodies each of unit mass having their centres placed at unit distance apart?

[A] It is equal to the force of attraction between them

[B] It is equal to twice the force of attraction between them

[C] It is equal to half the force of attraction between them

[D] It is equal to ten times the force of attraction between them

Correct Answer: [It is equal to the force of attraction between them]

Explanation: The universal gravitational constant is equal to the force of attraction between two bodies each of unit mass having their centres placed at unit distance apart. F = F = Gm1m2/r When m1 and m2 = 1 and r=1 then F=G.

### 23. Which of the following is true about the effect of altitude on the value of acceleration due to gravity?

[A] The acceleration due to gravity decreases with height

[B] The acceleration due to gravity increases with height

[C] The acceleration due to gravity is not dependent on height

[D] None of the above

Correct Answer: [The acceleration due to gravity decreases with height]

Explanation: The acceleration due to gravity decreases with height. G0= g(1-2h/R) where h is the height above the surface of the earth.

### 24. What is the dimensional formula of Gravitational Potential?

[A] M1 L2 T-2

[B] M1 L-2 T2

[C] M0 L2 T-2

[D] M0 L2 T2

Explanation: The dimensional formula of Gravitational Potential is M0 L2 T-2. It is a scalar quantity. S.I. unit of Gravitational Potential is J/kg.

### 25. What will be the effect on the value of acceleration due to gravity at the poles if the rate of rotation of earth increases?

[A] No effect

[B] it will increase

[C] it will decrease

[D] it will become zero

Explanation: If the rate of rotation of earth increases then the value of acceleration due to gravity decreases at all the places on the surface of earth except at poles.

### 26. What is the gravitational potential energy for infinite distance?

[A] 0

[B] infinity

[C] 9.8 J

[D] None of the above

Explanation: The gravitational potential energy of a body at a point is defined as the amount of work done in bringing the body from infinity to that point against the gravitational force. U = GMm/r When r =infinity, then U =0

### 27. Which of the following is correct about the value of acceleration due to gravity?

[A] it is greater at mountains than in plains

[B] it is lesser at mountains than in plains

[C] it is equal for mountains and plains

[D] None of the above

Correct Answer: [it is lesser at mountains than in plains]

Explanation: The value of acceleration due to gravity decreases with increase in height. Therefore, it is lesser at mountains than in plains.

### 28. The acceleration due to gravity on any planet does not depend on which of the following?

[B] Mass of the planet

[C] Density of the planet

[D] Mass of the object

Correct Answer: [Mass of the object]

Explanation: The value of acceleration due to gravity on any planet depends upon the mass radius and density of planet and it is independent of mass, shape and density of the body placed on the surface of the planet.

### 29. What do we call the minimum velocity with which a body must be projected up, so as to enable it to just overcome the gravitational pull?

[A] Orbital velocity

[B] Gravitational velocity

[C] Escape velocity

[D] None of the above

Explanation: The minimum velocity with which a body must be projected up, so as to enable it to just overcome the gravitational pull, is known as Escape velocity.

### 30. On which of the following the escape velocity of a body does not depend?

[A] Mass of the body

[C] Mass of the planet

[D] None of the above

Correct Answer: [Mass of the body]

Explanation: The escape velocity is independent of the mass and angle of projection of the body. Escape velocity depends on the mass and radius of the planet from the surface of which the body is to be projected.

### 31. The minimum speed required to put a satellite into a given orbit around earth is known as:

[A] Escape velocity

[B] Orbital velocity

[C] Kinetic velocity

[D] None of the above

Explanation: The minimum speed required to put a satellite into a given orbit around earth is known as Orbital velocity of the satellite. Orbital velocity (v) = (GM/r)1/2 where G= gravitational constant, M= mass of the earth and r = radius of the orbit of the satellite.

### 32. What happens to the orbital velocity of a satellite when the radius of orbit is increased?

[A] it decreases

[B] it increases

[C] it remains same

[D] None of the above

Explanation: The orbital velocity of a satellite decreases when the radius of orbit is increased or height of the satellite is increased.

### 33. What is the time period for a satellite orbiting close to the surface of earth?

[A] 84.6 minutes

[B] 72.4 minutes

[C] 44.8 minutes

[D] 24 hours

Explanation: In this case, the radius of the orbit will be nearly equal to the radius of earth i.e. 6.4 x 106m.The time period for a satellite orbiting close to the surface of earth is 84.6 minutes.

### 34. The angular momentum of a satellite depends on which of the following?

[A] Mass of the satellite

[B] Mass of the planet

[C] Radius of orbit of satellite

[D] All of the above

Correct Answer: [All of the above]

Explanation: The angular momentum of a satellite depends on: 1. Mass of the satellite, 2. Mass of the planet, 3. Radius of orbit of satellite it is denoted by L. L = (m2GMr)1/2

### 35. Which of the following is an essential condition for geostationary satellites of earth?

[A] It should rotate from west to east

[B] Its period of revolution should be 24 hours

[C] It should be at a height of nearly 36000 km above the equator

[D] All of the above

Correct Answer: [All of the above]

Essential condition for geostationary satellites of earth:

Its sense of rotation should be the same as that of earth i.e. it should rotate from west to east.

It should be at a height of nearly 36000 km above the equator.

Its period of revolution should be 24 hours.

it should revolve in an orbit concentric and coplanar with the equatorial plane.

Its orbital velocity is nearly 3.1 km/s

### 36. What is the relation between the orbital velocity and the radius of the orbit for a given planet?

[A] greater the radius of orbit, lesser will be the orbital velocity

[B] greater the radius of orbit, greater will be the orbital velocity

[C] orbital velocity is independent of radius of orbit

[D] None of the above

Correct Answer: [greater the radius of orbit, lesser will be the orbital velocity]

Explanation: For a given planet, greater the radius of orbit, lesser will be the orbital velocity of the satellite. The Orbital velocity depends on the mass of central body and radius of orbit.

### 37. What is the orbital velocity of geo stationary satellite?

[A] 4.15 km/s

[B] 2.78 km/s

[C] 3.08 km/s

[D] 6.66 km/s

Explanation: Orbital velocity of geo stationary satellite can be calculated as (GM/r)1/2. The orbital velocity of geo stationary satellite is 3.08 km/s.

### 38. What will be the total energy of a satellite moving around the earth in a circular orbit with speed v and having mass m.

[A] -1/2 m v 3

[B] 2 m v 2

[C] 1/2 m v 3

[D] -1/2 m v 2

Correct Answer: [ -1/2 m v 2]

Explanation: The total energy of a satellite moving around the earth in a circular orbit with speed v and having mass m is -1/2 m v 2

### 39. Which of the following states of matter has the weakest Intermolecular forces?

[A] Solids

[B] Liquids

[C] Gases

[D] It is same in solids, liquids and gases

Explanation: The three states of matter varies from each other due to the following factors. (1) The different magnitudes of the interatomic and intermolecular forces. (2) The extent of random thermal motion of atoms and molecules of a substance (which depends upon temperature). The Intermolecular force is strongest in solids and weakest in gases.

### 40. Which of these states of matter has the maximum density?

[A] Solids

[B] Liquids

[C] Gases

[D] None of the above

Explanation: The density is maximum in case of solids. In the case of liquids, the density is less than solids but more than gases. In gases, the density is minimum.

### 41. What is the order of distance for interatomic forces to be active?

[A] 10–7 metre

[B] 10–8 metre

[C] 10–9 metre

[D] 10–10 metre

Explanation: The forces between the atoms because of the electrostatic interaction between the charges of the atoms are called interatomic forces. These forces are active if the distance between the two atoms is of the order of atomic size i.e. 10–10metre. These forces are electrical in nature.

### 42. What is the equilibrium distance for Hydrogen atoms?

[A] 0.54 Å

[B] 0.64 Å

[C] 0.74 Å

[D] 0.84 Å

Explanation: When the interatomic force between two atoms is zero, the distance between them is called as normal or equilibrium distance. The equilibrium distance for Hydrogen atoms is 0.74 Å.

### 43. What happens to a body when its density is equal to the density of the fluid?

[A] it floats

[B] it sinks

[C] it remains suspended

[D] None of the above

Explanation: If the buoyant force equals the object’s weight, the object will remain suspended at that depth. If the buoyant force is greater than the object’s weight, the object will rise to the surface and float. If the buoyant force is less than the object’s weight, the object will sink. The buoyant force is always present whether the object floats, sinks, or is suspended in a fluid.

### 44. Which of the following is correct about Surface Tension?

[A] It is a scalar quantity

[B] It is a molecular phenomenon

[C] Its root cause is the electromagnetic forces

[D] All of the above

Correct Answer: [All of the above]

Explanation: Properties of Surface Tension: 1. it is a scalar quantity 2. it is a molecular phenomenon 3. its root cause is the electromagnetic forces.

### 45. When will the height of water in capillary tube be minimum?

[A] When water temperature is 0° C

[B] When water temperature is 4° C

[C] When water temperature is -4° C

[D] None of the above

Correct Answer: [When water temperature is 4° C]

Explanation: The height up to which water will rise in a capillary tube will be minimum when water temperature is 4° C. It is the temperature at which liquid water has the highest density.

### 46. What is the relationship between excess pressure and the radius of the bubble?

[A] are equal in value

[B] inversely proportional to each other

[C] directly proportional to each other

[D] no relationship

Correct Answer: [inversely proportional to each other]

Explanation: Excess pressure is inversely proportional to the radius of bubble (or drop). It means that the pressure inside a smaller bubble is higher than inside a larger bubble.

### 47. Which of the following intermolecular forces enables us to write on the blackboard with a chalk?

[A] Cohesive force

[C] both a and b

[D] None

Explanation: The force of attraction between the molecules of the different substances is called the force of adhesion. Adhesive force enables us to write on the blackboard with a chalk.

### 48. What is Specific Gravity of a liquid?

[A] ratio of the density of a liquid to the density of water

[B] product of the density of a substance to the density of water

[C] ratio of the density of water to the density of a liquid

[D] ratio of density of the liquid to the mass of the equal density of water

Correct Answer: [ ratio of the density of a liquid to the density of water]

Explanation: Specific gravity of a liquid is the ratio of the density of a substance to the density of water. The density of liquid water at standard conditions on earth is approximately 1,000 kg/m3.

### 49. What is the unit of Specific gravity?

[A] kg m-3

[B] kg m-2

[C] kg m-1

[D] No units

Specific gravity is a unitless quantity. Specific gravity is the ratio of two same dimensions. The dimension of density is M1 L-3

### 50. What is the density of water at 4°?

[A] 1.0

[B] 1.0 × 102 kg m–3

[C] 1.0 × 103 kg m–3

[D] 10 kg m–3

Correct Answer: [ 1.0 × 103 kg m–3]

Explanation: The density of water at 4°C (277 K) is 1.0 × 103 kg m–3. The relative density of a substance is the ratio of its density to the density of water at 4° C.

### 51. What happens to the viscosity of a liquid with increase in temperature?

[A] it increases

[B] it decreases

[C] it may increase or decrease

[D] No change

Explanation: The viscosity of liquids decreases with increase in temperature, while it increases in the case of gases.

### 52. What happens to the viscosity of a liquid with increase in temperature?

[A] it increases

[B] it decreases

[C] it may increase or decrease

[D] No change

Explanation: The viscosity of liquids decreases with increase in temperature, while it increases in the case of gases.

### 53. What is Reynolds number?

[A] ratio of inertial force to viscous force

[B] ratio of weight of fluid to viscous force

[C] ratio of velocity gradient to viscous force

[D] reciprocal of viscous force

Correct Answer: [ratio of inertial force to viscous force]

Explanation: Reynolds number is a dimensionless-number, whose value gives one an approximate idea whether the flow would be turbulent. The Reynolds number (Re) is the ratio of inertial force (force due to inertia i.e., mass of moving fluid or due to inertia of obstacle in its path) to viscous force.

### 54. What happens to the time period of a spring pendulum-based clock kept on the earth when it is taken to moon?

[A] Time period reduces to half

[B] Time period becomes twice

[C] Time period becomes one-sixth

[D] No change

Explanation: Time of a spring pendulum is independent of acceleration due to gravity. That is why a clock based on spring pendulum will keep proper time everywhere on a hill or moon or in a satellite and time period of a spring pendulum will not change inside a liquid if damping effects are neglected.

### 55. What is the relationship between mass and time period of a spring pendulum?

[A] T∝ 1/√m

[B] T ∝ √m

[C] T ∝ m

[D] √T ∝ m

Explanation: Time period of a spring pendulum depends on the mass suspended as T∝ √m i.e. greater the mass greater will be the inertia and so lesser will be the frequency of oscillation and greater will be the time period.

### 56. What is the relationship between the spring constant k and the spring length in case of spring pendulum?

[A] spring constant is inversely proportional to the spring length

[B] spring constant is directly proportional to the spring length

[C] spring constant is independent of the spring length

[D] spring constant is twice the spring length

Correct Answer: [spring constant is inversely proportional to the spring length]

Explanation: The spring constant of a spring pendulum is inversely proportional to the spring length.

### 57. Which of these is NOT an example of Periodic motion?

[A] Revolution of earth around the sun

[B] Rotation of earth about its polar axis

[C] Motion of minute’s hand of a clock

[D] None of the above

Correct Answer: [None of the above]

Explanation: Examples of Periodic motion: (i) Revolution of earth around the sun (period one year) (ii) Rotation of earth about its polar axis (period one day) (iii) Motion of hour’s hand of a clock (period 12-hour) (iv) Motion of minute’s hand of a clock (period 1-hour) (v) Motion of second’s hand of a clock (period 1-minute) (vi) Motion of moon around the earth (period 27.3 days).

### 58. What is the S.I unit of the propagation constant?

Explanation: The SI unit of propagation constant is radian per metre. It is also known as the angular wave number and represented by K.

### 59. Which of the following electromagnetic waves in the EM spectrum has the shortest frequency?

[B] Gamma

[C] X-rays

[D] Infrared

Explanation: The electromagnetic spectrum when arranged from the lowest to the highest frequency includes all radio waves (e.g., commercial radio and television, microwaves, radar), infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.

### 60. What is supersonic speed?

[A] When the speed of any object exceeds the speed of sound

[B] When the speed of any object exceeds the speed of light

[C] When the speed of any object exceeds 10000 m/s

[D] None of the above

Correct Answer: [When the speed of any object exceeds the speed of sound]

Explanation: When the speed of any object exceeds the speed of sound it is said to be travelling at supersonic speed. Bullets, jet aircrafts etc. often travel at supersonic speeds.

### 61. Which of the following are generally used to reduce reverberation in an auditorium as sound absorbents?

[A] compressed fibreboard

[B] rough plaster

[C] draperies

[D] All of the above

Correct Answer: [All of the above]

Explanation: To reduce reverberation, the roof and walls of the auditorium are generally covered with sound-absorbent materials like compressed fibreboard, rough plaster or draperies.

### 62. What is the S.I unit of heat energy?

[A] Joule

[B] Kelvin

[C] Candela

[D] Ampere

Explanation: The SI unit of heat energy transferred is expressed in joule (J) while SI unit of temperature is Kelvin (K), and degree Celsius (°C) is a commonly used unit of temperature.

### 63. Which of the following represents ideal gas law?

[A] PVT = constant

[B] PT/V = constant

[C] PV/T = constant

[D] VT/P = constant

Explanation: Since PV = constant and V/T = constant for a given quantity of gas, then PV/T should also be a constant. This relationship is known as ideal gas law.

### 64. Which of the following represents the absolute zero temperature?

[A] 0° C

[B] -100° C

[C] -273.15° C

[D] 273.15° C

Explanation: This temperature is found to be –273.15 °C and is designated as absolute zero. This is the absolute minimum temperature for an ideal gas.

### 65. What do we call the mode of transmission of heat by which heat travels from one part of a body to another by the actual motion of the heated particles of the body?

[A] Conduction

[B] Convection

[D] None of the above

Explanation: Convection is that mode of transmission of heat by which heat travels from one part of a body to another by the actual motion of the heated particles of the body.

### 66. What is a perfectly black body?

[A] A body which absorbs all the radiations incident on it

[B] A body which has zero coefficient of linear expansion

[C] A body which has zero absorptive power

[D] A body painted black on all sides

Correct Answer: [A body which absorbs all the radiations incident on it]

Explanation: A body which absorbs all the radiations incident on it is called a perfectly black body.

### 67. What is meant by Calorimetry?

[A] Measurement of heat

[B] Measurement of temperature

[C] Measurement of specific heat capacity

[D] None of the above

Explanation: Calorimetry means measurement of heat. A device in which heat measurement can be done is called a calorimeter.

### 68. Which of the following are Green-house gases?

[A] Carbon dioxide

[B] Methane

[C] Nitrous oxide

[D] All of the above

Correct Answer: [All of the above]

Explanation: Some of the green-house gases: carbon dioxide, methane, nitrous oxide, chlorofluorocarbon, tropospheric ozone.

### 69. What happens when light travels from a denser medium to a rarer medium?

[A] it slows down and bends towards the normal

[B] it speeds up and bends towards the normal

[C] it slows down and bends away from the normal

[D] it speeds up and bends away from the normal

Correct Answer: [it speeds up and bends away from the normal]

Explanation: A ray of light travelling from a rarer medium to a denser medium slows down and bends towards the normal. When it travels from a denser medium to a rarer medium, it speeds up and bends away from the normal.

### 70. Where will be the image formed by a convex lens when the object is placed at the focus?

[A] No image is formed

[B] At focus

[C] Between focus and optical centre

[D] At infinity

Explanation: The image is formed at infinity by a convex lens when the object is placed at the focus.

### 71. What are the dimensions of Co-efficient of volume expansion?

[A] T-1 K-1

[B] M2 K-1

[C] K-1

[D] M1 K-2

Explanation: The dimensions of Co-efficient of volume expansion is given by K-1

### 72. Which of the following statements state that no process is possible whose sole result is the transfer of heat from a colder object to a hotter object?

[A] Kevin-Plank statement

[B] Einstein’s statement

[C] Clausius statement

[D] None of the above

Explanation: Clausius statement: No process is possible whose sole result is the transfer of heat from a colder object to a hotter object.

### 73. Which of the following is true about a concave lens?

[A] power of a concave lens is positive

[B] power of a concave lens is negative

[C] power of a concave lens is zero

[D] None of the above

Correct Answer: [power of a concave lens is negative]

Explanation: The power of a convex lens is positive and that of a concave lens is negative.

### 74. Which of the phenomenon is due to the scattering of light?

[A] blue colour of sky

[B] reddening of the Sun at sunrise

[C] reddening of the Sun at sunset

[D] All of the above

Correct Answer: [All of the above]

Explanation: Scattering of light causes the blue colour of sky and the reddening of the Sun at the sunrise and sunset.

### 75. What causes the twinkling of stars?

[A] Atmospheric refraction of starlight

[B] Dispersion of starlight

[C] Scattering of starlight

[D] None

Correct Answer: [Atmospheric refraction of starlight]

Explanation: The twinkling of a star is due to atmospheric refraction of starlight. The starlight, on entering the earth’s atmosphere, undergoes refraction continuously before it reaches the earth.

### 76. What of the following represents linear magnification?

[A] ratio of the height of the image to the height of the object

[B] ratio of the height of the object to the height of the image

[C] product of the height of the object to the height of the image

[D] difference of the height of the image to the height of the object

Correct Answer: [ratio of the height of the image to the height of the object]

Explanation: The linear magnification (m) is defined as the ratio of the height of the image to the height of the object.

### 77. What is the phenomenon of bouncing back of light in the same medium on striking the surface of any object known as?

[A] Refraction

[B] Absorption

[C] Reflection

[D] Diffusion

Explanation: Reflection of light is the phenomenon of bouncing back of light in the same medium on striking the surface of any object.

### 78. As per Ohm’s law, if the resistance of a conductor is doubled, what will be the effect on the current flowing through it?

[A] it gets doubled

[B] it gets halved

[C] it increases 4 times

[D] No change

Explanation: As per Ohm’s law, if the resistance of a conductor is doubled, the electric current flowing through it gets halved. As per Ohm’s Law: R = V/I where R= Resistance, V= Potential Difference, I = Current.

### 79. Which of the following is true about metals?

[A] They are good conductors of electricity

[B] They have low resistivity

[C] Both a and b

[D] None of the above

Correct Answer: [Both a and b]

Explanation: The metals and alloys have very low resistivity in the range of 10–8 Ω m to 10–6 Ω m.They are good conductors of electricity.

### 80. Where is National Physical laboratory located in India?

[A] Pune

[B] New Delhi

[C] Mumbai

[D] Chennai

Explanation: National Physical laboratory is located at New Delhi.

### 81. What do we call an undoped semiconductor?

[A] Intrinsic semiconductor

[B] Extrinsic semiconductor

[C] p-type semiconductor

[D] None of the above

Explanation: An intrinsic semiconductor is an undoped semiconductor. This means that holes in the valence band are vacancies created by electrons that have been thermally excited to the conduction band.

### 82. What is the output of an AND gate when both the inputs are 0?

[A] 0

[B] 1

[C] Either 0 or 1

[D] 2

Explanation: The AND gate is a basic digital logic gate that gives a LOW output If none or not all inputs to the AND gate is HIGH.

### 83. Which of these diodes is used to detect optical signals?

[A] Photodiode

[B] Light emitting diode

[C] Photovoltaic diode

[D] None of the above

Explanation: Photodiode can be used as a photodetector to detect optical signals.

### 84. What happens to the resistance of a p-n junction diode when forward biased?

[A] it becomes high

[B] No effect

[C] it becomes low

[D] it becomes zero

Explanation: The resistance of a p-n junction diode becomes low when forward biased and becomes high when reverse biased. This is the principle of the working of rectifier.

### 85. What do we call the ratio of change in collector-emitter voltage to the resulting change in the collector current at constant base current, when the transistor is being used in Common Emitter configuration?

[A] Input dynamic resistance

[B] Output dynamic resistance

[C] Output emitter Current

[D] Input emitter Current

Explanation: Output dynamic resistance of Common Emitter transistor is ratio of change in collector-emitter voltage to the resulting change in the collector current at constant base current.

### 86. What is a p-n diode said to be in reverse-bias?

[A] positive terminal of the external battery is connected to the p-side

[B] positive terminal of the external battery is connected to the n-side

[C] negative terminal of the external battery is connected to the n-side

[D] None of the above

Correct Answer: [positive terminal of the external battery is connected to the n-side]

Explanation: If the positive terminal of the external battery is connected to the n-side and the negative terminal of the external battery is connected to the p- side, then the p-n junction is said to be reverse biased.

### 87. What is the value of Planck’s constant?

[A] 6.6 × 10–34 Js

[B] 3.6 × 10–34 Js

[C] 6.6 × 10–24 Js

[D] 6.6 × 10–17 Js

Correct Answer: [6.6 × 10–34 Js]

The value of Planck’s constant is 6.6 × 10–34 Js.

### 88. Which of these rays have the highest ionising power?

[A] Alpha

[B] Beta

[C] Gamma

[D] All have the same

Explanation: Alpha rays have the highest ionizing power followed by Beta rays and then Gamma rays.

### 89. What is the process which causes the elimination of one or more electrons from the atomic shell known as?

[A] Excitation

[B] Ionization

[C] Diffusion

[D] Refraction

Explanation: Ionization is any process which causes the addition of one or more extra electrons to the atomic shell or the elimination of one or more electrons from the atomic shell.

### 90. What of following is equivalent to 1 a.m.u?

[A] 1.660539 x 10-18 kg

[B] 1.660539 x 10-21 kg

[C] 1.660539 x 10-24 kg

[D] 1.660539 x 10-27 kg

Correct Answer: [1.660539 x 10-27 kg]

Explanation: 1 a.m.u = 1.660539 x 10-27 kg

### 91. Which of the following quantities indicate the degree of magnetization of a material in response to an applied magnetic field?

[A] Intensity of magnetization

[B] Magnetic permeability

[C] Magnetizing force

[D] Magnetic susceptibility

Explanation: Magnetic susceptibility indicate the degree of magnetization of a material in response to an applied magnetic field.

### 92. Which of the following properties of a material make it suitable to become a permanent magnet?

[A] The material should have high retentivity

[B] The material should have low coercivity

[C] The material should have low permeability

[D] Both b and c

Correct Answer: [The material should have high retentivity]

Explanation: The material should have high retentivity so that the magnet is strong and high coercivity so that the magnetisation is not erased by stray magnetic fields, temperature fluctuations or minor mechanical damage. Further, the material should have a high permeability.

### 93. What do we call an arrangement of two unlike poles of equal strength separated by a small distance?

[A] Magnetic dipole

[B] Solenoid

[C] Toroid

[D] Electric dipole

Explanation: Magnetic dipole is an arrangement of two unlike magnetic poles of equal pole strength separated by a very small distance.

### 94. Which of the following is NOT a natural magnet?

[A] lodestone

[B] pyrrhotite

[C] columbite

[D] titanium

Explanation: An example of a natural magnet is the lodestone, also called magnetite. Other examples are pyrrhotite, ferrite, and columbite.

### 95. What is the net magnetic field in a solenoid?

[A] product of the fields due to all the turns

[B] equal to the field due to the largest turn

[C] vector sum of the fields due to all the turns

[D] arithmetic mean of the fields due to all the turns

Correct Answer: [vector sum of the fields due to all the turns]

Explanation: The net magnetic field in a solenoid is the vector sum of the fields due to all the turns.

### 96. What is the direction of current through external circuit in a galvanic cell?

[A] flows from cathode to anode

[B] flows from anode to cathode

[C] flows in both direction

[D] None of the above

Correct Answer: [flows from cathode to anode]

Explanation: Current flows from cathode to anode through external circuit.

### 97. What do we call a device which generates electric energy using chemical energy?

[A] Potentiometer

[B] Resistor

[C] Cell

[D] Metre bridge

Explanation: A device which generates electric energy using chemical energy is known as a cell.

### 98. Which of the following is correct NOT correct about inert electrodes?

[A] They serve as source of electrons

[B] They take part in the chemical reaction

[C] Both a and b

[D] None of the above

Correct Answer: [They take part in the chemical reaction]

Explanation: An inert electrode is a metal submerged in an aqueous solution of ion compounds that transfers electrons rather than exchanging ions with the aqueous solution. It does not participate or interfere in the chemical reaction but serves as a source of electrons.

### 99. What do we call the cell that requires an outside electrical source to drive the non-spontaneous redox reaction?

[A] Voltaic cell

[B] Electrolytic cell

[C] Galvanic cell

[D] None of the above

Explanation: An Electrolytic cell is one kind of battery that requires an outside electrical source to drive the non-spontaneous redox reaction.

### 100. Which of the following cells is the basis of Non-rechargeable batteries?

[A] Galvanic cells

[B] Electrolytic cells

[C] Both a and b

[D] None of the above