Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
1. Zero point energy is the lowest possible energy that a quantum mechanical physical system may have. “Who among the following proposed this concept?
[A] Max Planck
[B] Albert Einstein and Otto Stern
[C] Hendrik B. G. Casimir
[D] Gribbin, John
Show Answer
Correct Answer: B [Albert Einstein and Otto Stern]
Notes:
Albert Einstein and Otto Stern proposed the concept of Zeropoint energy. It is the lowest possible energy that a quantum mechanical physical system may have.
2. Any moving object on earth finally comes to rest due to which among the following?
[A] Gravity
[B] Friction
[C] Inertia
[D] Motion
Show Answer
Correct Answer: B [Friction]
Notes:
Friction is the main reason for any object to come to rest. It is the main reason for the stability of the objects on earth.
3. A train travels at the speed of 180 km/hr. What is its speed in m/s?
[A] 5 m/s
[B] 30 m/s
[C] 40 m/s
[D] 50 m/s
Show Answer
Correct Answer: D [50 m/s]
Notes:
The speed of the train, given in kilometers per hour, is to be converted to meters per second. We use the conversion formula which states that 1 km/hr is equal to 5/18 m/s. Using the formula, we get (180 x 5)/18, which equals 50 m/s. This conversion is often applied in physics to accurately measure speed or velocity in different units for a variety of calculations, such as computation or comparison of speeds of different objects moving at varying velocities.
4. A person weighing 80 Kg. is standing on an accurate scale in an elevator. The elevator is slowing down while moving downwards. In this case the scale will read__?
[A] 80 Kg.
[B] Less than 80 Kg
[C] More than 80 Kg
[D] Either less or more than 80 Kg
Show Answer
Correct Answer: C [More than 80 Kg]
Notes:
When the elevator is slowing down while moving downwards, that means there is an acceleration upwards. The gravitational force must be lesser than the normal force. Thus, during slowing down while moving downwards, the normal force on the feet of a passenger is greater than her weight. In this case the scale will read more than 80 kg.
5. Which of the following is the unit of Solid Angle?
[A] radian
[B] steradian
[C] m2
[D] π
Show Answer
Correct Answer: B [ steradian ]
Notes:
Steradian is the unit of Solid Angle (Angle in Space). One steradian is defined as the solid angle of a sphere subtended at the centre of a sphere by that surface of the surface whose area is equal to the square of the sphere’s radius. Its symbol is sr.
6. Which of the following units is NOT used for measuring length?
[A] Astronomical Unit
[B] Light year
[C] Par sec
[D] slug
Show Answer
Correct Answer: D [ slug ]
Notes:
Astronomical Unit, Light year and Par sec are the units used to measure very large distances whereas slug is a unit to measure heavy masses. 1 slug = 14.57 kg
7. Power of lens is measured in which of the following units?
[A] metre
[B] dioptre
[C] lumen
[D] watt
Show Answer
Correct Answer: B [ dioptre ]
Notes:
Power of lens is measured in dioptre(D). Power of lens = 1/focal length The power of a lens is its ability to bend light. The greater the power the greater the refraction of light.
8. Which of the following pairs represent two scalar quantities?
[A] Mass, Acceleration
[B] Temperature, Torque
[C] Distance, Speed
[D] Gravitational Intensity, Work
Show Answer
Correct Answer: C [Distance, Speed]
Notes:
The physical quantities which have only magnitude and no direction are called as Scalar quantities. Some examples of Scalar quantities: Work, Mass, Temperature, Distance, Speed.
9. Which of the these physical quantities is a vector quantity?
[A] Temperature
[B] Speed
[C] Gravitational Intensity
[D] Work
Show Answer
Correct Answer: C [Gravitational Intensity]
Notes:
The physical quantities which have both magnitude and direction are called as Vector quantities. Some examples of Vector quantities: Acceleration, Velocity, Torque, Displacement, Gravitational Intensity, Force.
10. What is the angular acceleration of a body moving with constant angular velocity?
[A] equal to the angular velocity
[B] 1
[C] 0
[D] Can’t be determined
Show Answer
Correct Answer: C [0]
Notes:
The angular acceleration of a body moving with constant angular velocity is 0. Angular acceleration of an object in circular motion is defined as the time rate of change of its angular velocity.
