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 radiations in the Sunlight causes tanning and sunburn?
[A] Ultraviolet
[B] Visible
[C] Infrared
[D] Micro waves
Show Answer
Correct Answer: A [Ultraviolet]
Notes:
The sunlight that reaches the earth has ultraviolet A and ultraviolet B (UVA and UVB) rays. These ultraviolet rays are the main causes of damage to the skin from the sun. UVA and UVB rays affect the skin’s sensitivity to sun exposure in different ways.
2. Which among the following would be most commonly affected, if the filament of a electric Bulb is not uniform?
[A] Light
[B] Life
[C] Resistance
[D] None of the above
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Correct Answer: B [Life]
Notes:
If the filament of the bulb is affected then the life of the bulb is affected. Filament is very important for the bulb to function.
3. 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.
4. Which among the following explains the radiation emitted by black bodies?
[A] Big-bang theory
[B] Quantum Theory
[C] Piezoelectric Effect
[D] None of the above
Show Answer
Correct Answer: B [Quantum Theory]
Notes:
The correct answer is Quantum Theory. Black body radiation refers to the electromagnetic radiation emitted by an idealized object that absorbs all incident radiation. Max Planck introduced the concept in 1900, leading to the development of quantum mechanics. This theory explains that energy is quantized, emitted in discrete packets called quanta or photons, resolving the ultraviolet catastrophe predicted by classical physics.
5. In which of the following situations the force applied by the weight of a person becomes zero in a lift
[A] Lift moves up with an acceleration of 9.8 meter per sq. second
[B] Lift moves down with an acceleration of 9.8 meter per sq. second
[C] Lift moves up with an speed of 9.8 meter per second
[D] Lift moves up with down speed of 9.8 meter per second
Show Answer
Correct Answer: B [Lift moves down with an acceleration of 9.8 meter per sq. second]
Notes:
The weight of a person becomes zero in a lift. Lift moves down with an acceleration of 9.8 meter per sq. second.
6. In which of the following conditions, a Balloon filled with a gas such as Hydrogen will tend to rise up?
[A] If the buoyant force exerted by the air on a balloon is greater than the weight of the balloon
[B] If the buoyant force exerted by the air on a balloon is less than the weight of the balloon
[C] If the buoyant force exerted by the air on a balloon is equal to the weight of the balloon
[D] If the density of the air is greater than the density of the gas filled in balloon
Show Answer
Correct Answer: A [ If the buoyant force exerted by the air on a balloon is greater than the weight of the balloon]
Notes:
A Balloon filled with a gas such as Hydrogen gas is much lighter in weight than the weight of air displaced by it. So the buoyant force exerted by the air on a balloon is greater than the weight of the balloon. The hydrogen gas which is lighter than air enables the balloon to float.
7. A pressure cooker on a stove with its lid tightly closed and the whistle in position is an example of:
[A] open system
[B] closed system
[C] isolated system
[D] adiabatic system
Show Answer
Correct Answer: B [ closed system]
Notes:
A pressure cooker on a stove with its lid tightly closed and the whistle in position is an example of a closed-system thermodynamic process. In a closed-system thermodynamic process, the container (in this case, the pressure cooker) is sealed, and there is no exchange of matter with the surroundings. The pressure cooker is designed to be airtight, so no air or steam can escape while it’s cooking. This sealed environment allows for the buildup of pressure and temperature inside the cooker, which, in turn, speeds up the cooking process.
8. Who among the following is credited for the Corpuscular theory of light?
[A] Isaac Newton
[B] Christiaan Hyugens
[C] Albert Einstein
[D] James Clerk Maxwell
Show Answer
Correct Answer: A [Isaac Newton]
Notes:
The Corpuscular theory of light was given by Isaac Newton. It was replaced by Huygens’ wave theory when it failed to adequately explain the diffraction, interference and polarization of light. The Huygens’ wave theory was replaced by Planck’s quantum theory and finally de-Broglie’s Dual-Theory of light replaced all previous ones.
9. The energy by virtue of its position is known as:
[A] Kinetic energy
[B] Potential energy
[C] Internal energy
[D] Heat energy
Show Answer
Correct Answer: B [Potential energy]
Notes:
The energy by virtue of its position is known as Potential energy. The energy by virtue of its motion is known as Kinetic energy.
10. What is the gravitational potential energy for infinite distance?
[A] 0
[B] infinity
[C] 9.8 J
[D] None of the above
Show Answer
Correct Answer: A [0]
Notes:
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
