**Most Important MCQ’s of Physics**

Most Important MCQ’s of Physics : Here is a list of most important MCQ’s of Physics Part 1.Must revise these if you want to quickly go through all the book.We are damn sure these will help you a lot.And we are extremely sorry if you are unable to understand the statement or options of any question because some of the units are not supported by the editor format.

**SI units of solid angle is**

(a) radian (b) revolution

(c) degree (d) steradian

**Which one of the followings is not the SI unit of length?**

(a) angstrom (b) micron

(c) radian (d) parsec

**Which one of the followings is not the SI unit?**

(a) kg (b) mol

(c) °C (d) cd

**Which one of the followings is not the fundamental SI unit?**

(a) kelvin (b) ampere

(c) poise (d) metre

**Candela is the SI unit of**

(a) charge (b) luminous intensity

(c) power (d) refractive index

**2 kgm-3 when changed to gcm-3 reads**

(a) 1.2×10-1 (b) 1.2×10-2

(c) 1.2×10-3 (d) 1.2×10-4`

**Radius of a proton is equal to**

(a) 1.2×10-13 cm (b) 1.2×10-13 m

(c) 1.2×10-14 m (d) 1.2×10-10 m

**Which one of the followings represents the longest length?**

(a) 1.24×104 mm (b) 1.24×104 m

(c) 1.24×102 km (d) 1.24×103 dm

**Steradian is the angle subtended in**

^{ }Page 1 of 6

- two dimensions
- three dimensions
- both in two and three dimensions
- none of these

**The absolute uncertainty in the measurement 15.4 cm is**

(a) 0.1 cm (b) 0.01 cm

(c) 0.05 cm (d) 0.5 cm

**The fractional uncertainty in a measurement is defined as**- measured value – zero error
__measured value__ - error
- error ? measured value

- measured value – zero error

error

- measured value

**The fractional uncertainty in measurement 15.4 cm is**

(a). 0.006 (b) 0.0006

(c) 0.003 (d) none of these

**Which instrument is suitable for measuring the length of a metal bar about 10 cm long?**

(a) Screw gauge (b) Vernier Calliper

(c) Metre rod (d) External jaws of a calliper

**A metre rod is used to measure a length. The correct order of accuracy of the instrument is**

(a) 1 cm (b) 0.05 cm

(c) 0.01 cm (d) 0.1 cm

**A micrometer screw gauge is used to measure the diameter of a glass rod. The correct order of accuracy of the instrument is**

(a) 1 mm (b) 0.1 mm

(c) 0.01 mm (d) 0.0001mm

**Which one of the followings is not suitable for the measurement of time?**

(a) simple pendulum (b) pulse rate

(c) ticker timer (d) vibrating mass-spring system

**A simple pendulum can be used as a clock because**- its time period is 1 s
- its time period is constant
- its period of oscillation is same every where
- it does not stop oscillating

**One giga means**

(a) 109 (b) 10-9

(c) 10-12 (d) 1012

**One femto equals**

(a) 1015 (b) 1012

(c) 10-12 (d) 10-15

**One micrometer equals**

(a) 10-3 m (b) 10-6 m

(c) 10-5 m (d) 106 m

**An error of observation arising out of the negligence on the part of the person is called**

(a) random error (b) systematic error

(c) personal error (d) common error

**Use of faulty apparatus introduces an error called**

(a) experimental error (b) designing error

(c) random error (d) systematic error

**Random error can be corrected by**- taking an observation carefully
- using a precise instrument
- taking several observations
- calibrating the instrument

**Causes of systematic error in an instrument are**

(a) unknown (b) known

(c) arbitrary (d) none of these

**Significant figures in a measured value indicate**- the reading on an instrument
- doubtful numbers
- quantity which is reasonably reliable
- accurate numbers

**The number of significant figures in the value 0.09810 are**

(a) 4 (b) 3

(c) 6 (d) 5

**The number of significant figures in the value 1.90 ? 10-31 are**

(a) 34 (b) 28

(c) 3 (d) 2

**The dimensions of weight are equal to the dimensions of**

(a) weight density (b) mass density

(c) pressure (d) force

**When rounded off to three significant figures, the value**

**6.735 should be written as**

(a) 6.73 (b)6.70

(c) 6.74 (d) none of these

**845 is to be rounded off to three significant figures. The value should be written as**

(a) 9.84 (b) 9.85

(c) 9.80 (d) none of these

**Given F = t + bt dimensions of a and b are respectively**

(a), [MLT-1] and [MLT-4] (b) [LT-1] and [T-2]

(c) [T] and [T-2] (d) [LT-2] and [T-2]

**The dimensions of angular displacement are**

(a) [L] (b) [LT-1]

(c) [L2] (d) [L^{0}]

**Which of the following quantities is not dimensionless?**

(a) angle (b) stress

(c) Young’s modulus (d) relative density

**The dimensional formula for energy per unit area per second is**

(a) [MT-1] (b) [MLT-1]

(c) [ML2T-1] (d) [MT-3]

**Use of dimensional analysis involves in**- finding the units of a quantity
- deriving a mathematical formula
- checking the correctness of an equation
- all of these

**Numbers carry**

(a) no dimensions (b) arbitrary dimensions

(c) dimensions but no units (d) all of these

**Only those terms can be added or subtracted which have**

(a) different dimensions (b) same dimensions

(c) no dimensions (d) none of these

**The dimensions of angular velocity are**

-1 -1

(a) [LT ] (b) [T ]

2 -1

(c) [L T ] (d) none of these

**The travel time of light from Earth to the moon (average**

**8 distance = 3.86 ? 10 m) is about** (a) 8 seconds (b) 1.20 seconds

(c) 1.20 minutes (d) 12 seconds

**CHAPTER 2**

1. **Which one of the followings is a scalar?**

(a) Energy (b) Velocity

(c) Force (d) Torque

2. **Which one of the followings is a vector?**

(a) Length (b) Volume

(c) Velocity (d) Work

3. **In which one of the followings are all the three quantities vectors?**

(a) Displacement, velocity, energy

(b) Force, work, energy

(c) Displacement, velocity, momentum

(d) Velocity, acceleration, power

4. **The reverse process of adding two vectors is called**

(a) multiplication (b) subtraction

(c) resolution (d) none of these

5. **The resultant of two vectors of equal magnitude inclined at some angle is equal to the magnitude of either of the two vectors. The angle between the two is**

(a) 60° (b)90°

(c) 120° (d) 180°

7. **Which figure represents R = U – V?**

8. **The result of adding A into – A is**

(a) A (b) 2 A

(c) O (d) 0

10. **When a certain vector is multiplied by – 1, then the direction of the vector changes through**

(a) 90° (b) 120°

(c) 150° (d) 180°

11. **Rectangular components make an angle of**

(a) 0° (b) 60°

(c) 90° (d) 120°

12. **The minimum number of unequal forces whose vector sum is zero must be**

(a) 1 (b) 2

(c) 3 (d) 4

13. **One of the rectangular components of a velocity of**

**50 ms-1 is 30 ms-1. The other component in ms-1 is**

(a) 15 (b) 20

(c) 25 (d) 40

^ ^

14. **For the two vectors Ax = (20 N) i , Ay= (20 N) j , the angle made by the resultant vector A with the x-axis is**

(a) 45° (b) 135°

(c) 215° (d) 315°

15. **Which of the following forces cannot be added to give of a resultant of 2 N?**

(a) 1 N and 1 N (b) 1 N and 2 N

(c) 2 N and 2 N (d) 1 N and 3 N

17. **Two forces act together on an object. The magnitude of their resultant is least when the angle between them is**

(a) 45° (b) 60°

(c) 90° (d) 180°

18. **If |A+B| = |A – B| where A and B are two vectors of equal magnitudes, then the angle between A and B is**

(a) 0° (b) 60°

(c) 90° (d) 180°

^ ^

19. **The angle subtended by r = 3 i + 4 j with x-axis is**

(a) 53° (b) 30°

(c) 41° (d) 60°

^ ^

20. **The magnitude of a vector A = Ax i – Ay j is**

(a) A2x + A2y (b) Ax2 + A2y

(c) A2x – A2y (d) A2x – A2y

21. **The dot product of two non-zero vectors equals the product of their magnitudes only if the angle between them is**

(a) 0° (b) 90° (c) 120° (d) 180°

22. **For which of the followings pair of angles, the dot product of two vectors is equal to the one half of the product of magnitudes of two vectors?**

(a) 60° and 120° (b) 60° and 240°

(c) 60° and 300° (d) none of these

23.** For a vector A,**

(a) A • A = 0 (b) A • A = 1

(c) A • A = A (d) A • A = A2

24. **Which one of the followings is correct?**

^ ^ ^ ^ ^

(a) i • j = k (b) i • j = 0

^ ^ ^ ^ ^

(c) i • j = 1 (d) i • j = –k

^ ^ ^

25.** Given A = 2i – 2j + k , the magnitude of this vector is**

(a) 1 (b) 2

(c) 3 (d) 5

26. **If A ? B lies along + z-axis, the vectors A and B will be in**

(a) xz-plane (b) xy-plane

(c) yz-plane (d) x-direction only

27. **The cross product of two non-zero parallel vectors A and B is**

(a) AB sin ? (b) AB

^

(c) AB sin ? n (d) O

29.** If A = Ax i + Ay j and B = Bx i + By j are two non-**

parallel vectors, then the direction of A ? B is along

(a) A (b) B

(c) x-axis (d) z-axis

30.** If A = A1 i + A2 j and B = B1 i + B2 j , the number of components in the vector A ? B is**

(a) 1 only (b) 2 only

(c) 3 only (d) 4 only

31.** If A • B = 0 and A xB = 0, then**

(a) either A or B is a null vector.

(b) A and B are non-parallel.

(c) A and B are perpendicular to each other.

(d) A and B are parallel to each other.

32. **The vector product is**

(a) commutative (b) anticommutative

(c) associative (d) additive

33. **The cross product of two vectors has a magnitude equal to the product of their magnitudes. Their dot product is equal to**

(a) AB sin? (b) AB cos?

(c) AB (d) 0

34. **Torque produced by a force depends upon**

(a) magnitude of the force and the angular velocity

(b) magnitude of the force and displacement (c) magnitude of the force and moment arm (d) force and acceleration of the body.

35. **A couple consists of**

(a) two equal and opposite forces acting at two different points on the body

(b) two equal and parallel forces acting at two different points (c) two equal and opposite force acting at a point on the body (d) two equal and parallel force acting at a point on the body.

36. **The arm of a couple is**

(a) any distance between the forces

(b) the shortest distance between the forces

(c) perpendicular distance between the two forces (d) the longest distance between the two forces.

37.** If the resultant of all the forces acting on a body is zero, then the body**

(a) has angular momentum (b) has acceleration

(c) is at rest (d) is in translational equilibrium

38. **Three coplanar forces acting on a body keep it in equilibrium. The forces must be**

(a) collinear (b) concurrent

(c) non-concurrent (d) parallel

39. **If the line of action of the force passes through the axis of rotation, then the torque is**

(a) zero (b) maximum

(c) clockwise in direction (d) counter clockwise in direction

Key to Test Chapter 2

1 a 21 a

2 c 22 c

3 c 23 d

4 c 24 b

5 c 25 c

6 d 26 b

7 b 27 d

8 c 28 d

9 c 29 d

10 d 30 a

11 c 31 a

12 c 32 b

13 d 33 d

14 a 34 c

15 b 35 a

16 a 36 c

17 d 37 d

18 c 38 b

19 a 39 a

20 b 40 d

**Chapter 3**

3. **A body whose instantaneous and average velocities are equal is said to have**

(a) constant acceleration (b) constant velocity

(c) variable velocity (d) variable acceleration

4. **Inertia of a body is a measure of its**

(a) mass (b) weight

(c) velocity (d) momentum

7. **Change of linear momentum of a body is called its (a) acceleration (b) impulse**

(c) force (d) energy

8. **A trolley of mass 3 kg moving with a speed of 4 ms?1 collides with and remains attached to a stationary trolley of mass 1 kg. Their combined momentum, in kg ms?1, after the collision is**

(a) 4 (b) 7

(c) 8 (d) 12

9. **Forces in nature always occur in**

(a) single form (b) pair form

(c) triple form (d) any form

10. **When two bodies move like a single body after colliding each other, the collision is said to be**

(a) perfectly elastic (b) partially elastic

(c) perfectly inelastic (d) partially inelastic

11. **As a result of an elastic collision between two masses m1 and m2 an exchange of velocity takes place. For collision of this type**

(a) m1 >> m2 (b) m1 = m2

(c) m1 << m2

(c) one of the masses must be initially at rest

12. **If a shell is fired from a canon and explodes in air, then the total**

(a) momentum increases (b) momentum decreases

(c) kinetic energy increases (d) kinetic energy decreases

13. **A ball thrown up with a velocity of 19.6 ms?1 returns back into the thrower’s hand after**

(a) 1 s (b) 2 s

(c) 3 s (d) 4 s

14. **Lead balls each of mass m kg fall on a horizontal plate at the rate of n balls per second. If they strike the plate with a velocity of v ms?1 , the force exerted on the plate in N is**

mv

(a) mvn (b)

n mn m (c) (d) v nv

15.** From the top of a building a ball A is dropped while another ball B is thrown horizontally at the same instant. Which ball will strike the ground first?**

(a) A (b) B

(c) Both at the same time (d) Nothing can be predicted

16.** In case of projectile motion, the maximum height attained by a body is equal to its range. The angle of projection with the horizontal is**

(a) tan?1 (1) (b) tan?1 (2)

(c) tan?1 (3) (d) tan?1 (4)

17. **The height H gained by a projectile is related to its maximum range Rmax by**

** R max**

(a) H = 4 Rmax (b) H?

4

R max (c) H = 2 Rmax (d) H?

2

18. **The horizontal range of a projectile is the same for the angles**

(a) 600 and 800 (b) 400 and 700

(c) 450 and 550 (d) 400 and 500

19. **The time taken by a projectile to reach maximum height is**

(a) v i sin? (b) 2vi sin?

2 g g

(c) v i sin? (d) vi cos? g g

20. **A ballistic trajectory is the path followed by**

(a) an un-powered and unguided missile

(b) a powered and guided missile

(c) an un-powered but guided missile

(d) a powered and guided missile

21.** A snooker ball moving with velocity v collides head-on with another snooker ball of same mass at rest. If the collision is elastic, the velocity of the second snooker ball is**

(a) zero (b) uncertain

(c) v (d) 2 v

22. **The time of flight of a projectile is**

(a) v i sin? (b) 2vi sin? g g

(c) v i sin? (d) 2vi cos?

23.** The velocity of a projectile at the maximum height is**

(a) vi sin? (b) vi cos???

(c) maximum (d) zero

24. **With increasing angle of projection, the vertical height gained by a projectile**

(a) decreases gradually

(b) increases gradually

(c) first increases and then decreases (d) remains the same.

25.** The horizontal component of the velocity of a projectile moving with initial velocity of 500 ms-1 at an angle of 600 to the x-axis is**

(a) 500 ms-1 (b) 1000 ms-1

(c) 250 ms-1 (d) zero

26. **A car is decelerating uniformly, its velocity changing from 30 ms?1 to 15 ms-1 in 75 m. How much further will it travel before coming to rest?**

(a) 25 m (b) 50 m

(c) 75 m (d) 100 m

28. **Laws of motion are valid in those systems which**

(a) are non-inertial (b) are inertial

(c) are at rest (d) are in space

29. **The force F exerted on a body colliding with F another body changes with time as shown. The area under the F – t graph represents the body’s change of**

(a) velocity (b) acceleration T (c) momentum (d) kinetic energy

31. **Neutron (mass = 1 u) undergoes elastic collision with stationary nitrogen nucleus (mass = 14 u). The velocity of neutron after the collision is**

(a) 0

(b) less than the velocity of nitrogen atom after collision

(c) equal in magnitude to its initial velocity but opposite direction

(d) less in magnitude than its initial velocity but with changed direction

32.** Area under the velocity – time graph represents**

(a) speed (b) momentum

(c) velocity (d) distance covered

33. **A body thrown up with a velocity of 9.8 ms?1 reaches a maximum height of**

(a) 9.8 m (b) 4.9 m

(c) 19.6 m (d) 44.1 m

34. **A force of 4 N acting on a body of mass 2 kg for 2 s produces a rate of change of momentum of**

(a) 1 kgms-1 (b) 2 kgms-1

(c) 4 kgms-1 (d) 8 kgms-1

35. **Dimensions of impulse are**

(a) [MLT] (b) [MLT-1]

(c) [MLT2] (d) [MLT?2]

36. **Collisions of gas molecules with the walls of the container are the example of**

(a) inelastic collisions (b) elastic collisions

(c) partially elastic collisions (d) partially inelastic collisions

37. **Gas molecules inside a container constitute**

(a) an isolated system (b) a non-isolated system

(c) a conservative system (d) a non-conservative system

38. **A ball bouncing off a wall**

(a) obeys law of conservation of energy

(b) does not obey law of conservation of energy (c) obeys law of conservation of momentum

(d) does not obey law of conservation of momentum.

39. **Speed of a projectile is minimum at the**

(a) point of landing (b) point of projection

(c) maximum height (d) none of these

40. **What happens when a system of two bodies undergoes an elastic collision?**

(a) The momentum of the system changes

(b) The momentum of the system does not change

(c) The bodies come to rest after collision (d) The energy conservation law is violated.

**Key to Test Chapter 3**

1 c 21 c

2 a 22 b

3 b 23 b

4 a 24 b

5 c 25 c

6 b 26 a

7 b 27 b

8 d 28 b

9 b 29 c

10 c 30 b

11 b 31 d

12 b 32 d

13 d 33 b

14 a 34 d

15 c 35 b

16 d 36 b

17 b 37 a

18 d 38 d

19 c 39 c

20 a 40 b

__Key to Test Chapter 1__

1 | d | 21 | a |

2 | c | 22 | d |

3 | c | 23 | c |

4 | c | 24 | b |

5 | b | 25 | c |

6 | c | 26 | a |

7 | c | 27 | c |

8 | c | 28 | d |

9 | b | 29 | c |

10 | a | 30 | a |

11 | d | 31 | d |

12 | a | 32 | a |

13 | b | 33 | d |

14 | d | 34 | b |

15 | c | 35 | d |

16 | b | 36 | d |

17 | b | 37 | a |

18 | a | 38 | b |

19 | d | 39 | b |

20 | b | 40 | b |

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