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.
31. Which phenomena shows the particle nature of light?
[A] Polarisation
[B] Diffraction
[C] Photoelectric effect
[D] Interference
Show Answer
Correct Answer: C [Photoelectric effect]
Notes:
The photoelectric effect is the emission of electrons or other free carriers when light falls on a material. Electrons emitted in this manner can be called photoelectrons. It shows the particle nature of light.
32. Neil Armstrong was the first person to reach on the moon. While walking on the moon what happens to his mass and weight?
[A] His mass remained the same but weight increased
[B] His mass remained the same but weight decreased
[C] His mass as well as weight decreased
[D] His mass increased but weight remained the same
Show Answer
Correct Answer: B [His mass remained the same but weight decreased]
Notes:
Mass is a measure of the amount of matter that an object has, or how much “stuff” it is made up of. Weight is a measure of how much gravity pulls on a mass or object. Mass doesn’t change when gravity changes. The mass on the moon would be the same as the mass on earth. The force due to gravity is 1/6 that of Earth, so he will weigh 1/6 of Earth weight.
33. The total internal reflection occurs when light travels in which of the following situations?
[A] A rarer medium to a denser medium
[B] A denser medium to a rarer medium
[C] A rarer medium to a denser medium and the angle of incidence is less than the critical angle
[D] A rarer medium to a denser medium and the angle of incidence is greater than the critical angle
Show Answer
Correct Answer: B [A denser medium to a rarer medium]
Notes:
When light travels from one medium to another it changes speed and is refracted. For total internal reflection to occur the light must travel from a dense medium to a less dense medium (e.g. glass to air or water to air). As the angle of incidence increases so does the angle of refraction.
34. Atmospheric pressure exerted on earth is due to the which of the following reasons?
[A] Rotation of earth
[B] Revolution of earth
[C] Gravitational pull
[D] Uneven heating of earth
Show Answer
Correct Answer: C [Gravitational pull]
Notes:
The atmospheric pressure at the surface of the Earth is due to gravitational pull of the earth and is about 14.7 psi. That means that the weight of a column of air which has a cross section of 1 square inch and which stretches from the surface of the Earth to space is 14.7 pounds.
35. Which colour of light in visible spectrum has highest energy?
[A] Red
[B] Violet
[C] Blue
[D] Green
Show Answer
Correct Answer: B [Violet]
Notes:
Violet colour in visible spectrum is having highest energy and least wavelength among all the components of visible spectrum.
Descending order of energies : Violet>Indigo>Blue>Green>Yellow>Orange>Red.
36. Which among the following is a scalar quantity?
[A] Velocity
[B] Distance
[C] Acceleration
[D] Displacement
Show Answer
Correct Answer: B [Distance]
Notes:
Scalar quantity is a physical quantity which has only magnitude but not direction whereas vector quantities have both magnitude and direction.
37. What is the charge of beta particle emitted in the radioactive decay?
[A] Positive
[B] Negative
[C] Neutral
[D] Charges switches regularly
Show Answer
Correct Answer: B [Negative]
Notes:
Alpha, beta and gamma radiations are emitted during the radioactive decay process. Alpha is positive particle with double positive charge, beta particle is an electron and hence negative charge, gamma radiation is neutral.
38. Match the following items of column (A) with column (B):
Column A
- I. Electron
- II. Proton
- III. Neutron
Column B
- Rutherford
- Thomson
- Chadwick
[A] I – 3, II – 1, III – 2
[B] I – 2, II – 1, III – 3
[C] I – 2, II – 3, III – 1
[D] I – 1, II – 2, III – 3
Show Answer
Correct Answer: B [I – 2, II – 1, III – 3]
Notes:
- Electron: discovered by J.J. Thomson in 1897 when he was studying the properties of cathode ray;
- Proton: discovered by Ernest Rutherford, in his famous gold foil experiment;
- Neutron: discovered by Sir James Chadwick, an English physicist, in 1932.
39. During _______ motion of an object along a straight line, the change in velocity of the object for any time interval is zero.
[A] linear
[B] translational
[C] equilibrium
[D] uniform
Show Answer
Correct Answer: D [uniform]
Notes:
During uniform motion of an object along a straight line, the velocity remains constant with time. In this case, the change in velocity of the object for any time interval is zero. This means, in the case of uniform motion, the rate of change of velocity, i. e. acceleration is equal to zero.
40. When a piece of stone is immersed in water, it displaces water of equal__:
[A] Density
[B] Specific gravity
[C] Mass
[D] Volume
Show Answer
Correct Answer: C [Mass]
Notes:
Archimedes’ Principle states that upward buoyant force exerted on a body immersed in a fluid is equal to the weight of the fluid displaced by the body immersed in the fluid.
