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. Which among the following is a source of Atomic Energy ?
[A] Iron
[B] Uranium
[C] Silver
[D] Platinum
Show Answer
Correct Answer: B [Uranium]
Notes:
Uranium is the most common fuel used to produce nuclear energy. Uranium is a nonrenewable energy source that is found in rocks all over the world. However, the specific type of uranium used to produce nuclear energy, called U-235, is rare.
2. Which among the following is true about Total Internal Reflection?
[A] A ray passing from rarer to denser medium and not able to pass to denser medium at an angle greater than critical angle
[B] A ray passing from denser to rarer medium and not able to pass to rarer medium at an angle greater than critical angle
[C] A ray passing from either denser to rarer medium or rarer to denser medium and not able to pass any medium at an angle smaller than critical angle
[D] None of the above
Show Answer
Correct Answer: B [A ray passing from denser to rarer medium and not able to pass to rarer medium at an angle greater than critical angle]
Notes:
A ray passing from denser to rarer medium and not able to pass to rarer medium at an angle greater than critical angle. Critical angle is the angle in which the incident ray is 90 degrees to that of the refracted ray.
3. A transition from the solid to gas phase with no intermediate liquid stage is called?
[A] Evaporation
[B] Sublimation
[C] Adsorption
[D] Solid Phase extraction
Show Answer
Correct Answer: B [Sublimation]
Notes:
Sublimation is the process by which a substance transitions from a solid to a gas without passing through a liquid phase. This typically occurs when a substance is heated to a temperature at which its solid form becomes a gas, such as when dry ice (solid carbon dioxide) sublimates and turns into gas. Sublimation can also occur when a substance is exposed to a vacuum, which can cause gases to be drawn out of the substance and turn into a solid. Sublimation is an important process in many scientific and industrial fields, including meteorology, chemistry, and materials science. Camphor is also an example of Sublimation.
4. Two Flat mirrors are placed at an angle of 60° from each other. How many images will be formed of a Candle placed in between them?
[A] 3
[B] 4
[C] 5
[D] 6
Show Answer
Correct Answer: C [5]
Notes:
If two flat mirrors are placed at an angle ø. Then number of images of an object placed between mirrors are = (360/ø) – 1 .
Here ø = 60
So, number of images of candle = (360/60) -1
SO there will be 5 images.
5. In recent times, the “dynamic brake system” is becoming popular in modern railways. The dynamic brake system coverts Kinetic energy to__:
[A] Potential energy
[B] Electricity
[C] Sound energy
[D] Magnetic energy
Show Answer
Correct Answer: B [ Electricity]
Notes:
Modern engines also have, additionally, dynamic brake system which works on the principle of converting kinetic energy of the moving train to electricity making the electric motors to work as generators.
6. What is the change in the angular momentum of a system as per the Law of Conservation of Angular momentum, if the total external torque acting is zero?
[A] Remains constant
[B] Becomes zero
[C] Increases exponentially
[D] None of the above
Show Answer
Correct Answer: A [Remains constant]
Notes:
Law of Conservation of Angular Momentum: if the total external torque acting on a system is zero, the angular momentum of a system remains constant. Angular Momentum is the momentum associated with the rotation of an object. Angular Momentum = moment of Inertia X angular Speed
7. The equation of motion ‘v = u +at’ can be applied in which of the following cases?
[A] simple harmonic motion
[B] circular motion
[C] when acceleration is constant
[D] Both b and c
Show Answer
Correct Answer: C [when acceleration is constant]
Notes:
The equation of motion ‘v = u +at’ can be applied only when the acceleration is constant. It cannot be applied in the cases of simple harmonic motion and circular motion.
8. When one body is actually moving over the surface of other body, the friction is known as:
[A] Kinetic friction
[B] Limiting friction
[C] Static friction
[D] Negative friction
Show Answer
Correct Answer: A [Kinetic friction]
Notes:
When one body is actually moving over the surface of other body, the friction is known as Kinetic friction. It is also known as dynamic friction.
9. The Newton’s third law is applicable when:
[A] bodies are at rest
[B] bodies are in motion
[C] bodies are in the air
[D] bodies are at rest or in motion
Show Answer
Correct Answer: D [bodies are at rest or in motion]
Notes:
The Newton’s third law is applicable whether the bodies are at rest or in motion. It states that to every action there is an equal and opposite reaction.
10. 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
Show Answer
Correct Answer: A [The acceleration due to gravity decreases with height]
Notes:
The acceleration due to gravity decreases with height. G0= g(1-2h/R) where h is the height above the surface of the earth.
