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. India’s first Nobel Prize for Physics was claimed in 1930 by the renowned physicist Sir C.V. Raman for his work in which among the following fields?
[A] Particle Physics
[B] Optics
[C] Thermodynamics
[D] Quantum Mechanics
Show Answer
Correct Answer: B [Optics]
Notes:
In 1930, C.V. Raman became the first person from Asia to be awarded a Nobel Prize in any field of science. CV Raman made significant contributions to the field of optics. He is best known for his discovery of the Raman effect, which is the scattering of light by molecules. This phenomenon is now known as Raman scattering. The date of the discovery, February 28, is now celebrated as National Science Day in India.
2. Which among the following sentence is correct reason behind the blue color of ocean water?
[A] Water molecules absorb all other colors except blue
[B] Impurities in Sea water reflect the blue light
[C] Water molecules scatter the blue light
[D] None of the above
Show Answer
Correct Answer: C [Water molecules scatter the blue light]
Notes:
Water molecules scatter the blue light by absorbing the light waves and then rapidly re-emitting the light waves in different directions. That is why there are mostly blue wavelengths that are reflected back to our eyes.
3. If earth stops rotating, the impact on weight of a body will be minimum on which among the following places?
[A] Equator
[B] North Pole
[C] Tropic of Cancer
[D] Tropic of Capricorn
Show Answer
Correct Answer: B [North Pole]
Notes:
The question is related to the centrifugal forces, which represent the effects of inertia that arise in connection with rotation and which are experienced as an outward force away from the center of rotation. The impact of this force is maximum at Equator and minimum at Pole.
4. An object is executing uniform circular motion. Which of the following quantities remain(s) constant during the object’s motion?
[A] Velocity and acceleration
[B] Speed and velocity
[C] Speed and acceleration
[D] Speed only
Show Answer
Correct Answer: D [ Speed only]
Notes:
The velocity of an object undergoing uniform circular motion is always changing (because the direction is always changing). Further, since the acceleration is centripetal, it must always point toward the center of the circle; so, as the object moves around the circle, the acceleration vector is also constantly changing direction. Notice that for an object in uniform circular motion, both the velocity and the acceleration are changing because the directions of these vectors are always changing, even though their magnitudes stay the same. In this question, only speed remains unchanged.
5. For any object on the surface of earth, which among the following properties will be directly proportional to each other?
[A] It’s acceleration and it’s mass
[B] It’s mass and it’s weight
[C] It’s weight and it’s acceleration
[D] It’s speed and it’s velocity
Show Answer
Correct Answer: B [ It’s mass and it’s weight]
Notes:
The weight of an object and its mass are directly proportional. For a given gravitational field strength, the greater the mass of the object, the greater its weight.
6. In which among the following, the speed of sound would be maximum?
[A] Dry air at 0°C
[B] Dry air at 30°C
[C] Humid air at 0°C
[D] Humid air at 30°C
Show Answer
Correct Answer: D [ Humid air at 30°C]
Notes:
The speed of sound in a medium depends on temperature of the medium. The speed of sound decreases when we go from solid to gaseous state. In any medium as we increase the temperature the speed of sound increases.. The speed of sound will be highest in humid air at 30°C.
7. Electron microscope works on which of the following principles?
[A] Optical interference
[B] Wave Nature of electrons
[C] Motion of charged particle in electromagnetic fields
[D] Faraday’s law of Electromagnetic induction
Show Answer
Correct Answer: B [Wave Nature of electrons]
Notes:
Electron microscope works on the principle of Wave Nature of electrons. Electron microscopes use an electron beam instead of visible light and an electron detector instead of our eyes. An electron beam allows us to see at very small scales because electrons can also behave as light due to its wave nature.
8. Who among the following is credited for the discovery of ‘Expanding Universe’?
[A] Edwin Hubble
[B] Niels Bohr
[C] S Chandra Shekhar
[D] C.V Raman
Show Answer
Correct Answer: A [Edwin Hubble]
Notes:
Edwin Hubble, an american astronomer, and was the first to prove that the universe is expanding. According to Expanding Universe theory, the universe is presently expanding. Hubble proved that there is a direct relationship between the speeds of distant galaxies and their distances from Earth. This is now known as Hubble’s Law.
9. Which of the following is correct about the coefficient of limiting friction between any two surfaces in contact?
[A] it is equal to twice the tangent of angle of friction
[B] it is equal to twice the sine of angle of friction
[C] it is equal to the tangent of angle of friction
[D] it is equal to the sine of angle of friction
Show Answer
Correct Answer: C [it is equal to the tangent of angle of friction]
Notes:
The coefficient of limiting friction between any two surfaces in contact is equal to the tangent of angle of friction between them. u = tan Q where u = coefficient of limiting friction and Q = angle of friction
10. The Universal Gravitational Constant for two bodies is dependent on which of the following?
[A] Nature of the bodies
[B] Size of the bodies
[C] Nature of medium between the bodies
[D] None of the above
Show Answer
Correct Answer: D [None of the above]
Notes:
The value of Universal Gravitational Constant is same throughout the universe. It is independent of nature of the bodies, size of the bodies and nature of medium between the bodies.
