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 kinds of lenses are used to treat Astigmatism?
[A] Convex Lens
[B] Concave Lens
[C] Bifocal Lens
[D] Cylindrical
Show Answer
Correct Answer: D [Cylindrical]
Notes:
Astigmatism is due to imperfect spherical nature of eye lens. The focal length of eye lens is in two orthogonal directions become different so they cannot see objects in two orthogonal directions simultaneously. This defect in direction can be removed by using cylindrical lens in a particular direction.
2. 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.
3. The term “Isopycnic” is most closely defined by which among the following?
[A] Two places with same atmospheric pressure
[B] Two liquids with same viscosity
[C] Two liquids with same density
[D] Two places with same temperature
Show Answer
Correct Answer: C [Two liquids with same density]
Notes:
The term “Isopycnic” refers to two substances having the same density. It is derived from the Greek words “iso,” meaning equal, and “pycnos,” meaning dense. In scientific contexts, isopycnic conditions are often used in centrifugation techniques to separate particles based on their density, such as in the purification of DNA or proteins.
4. If a moving body turns its speed to 1.5 times, what will be the impact on its kinetic energy?
[A] will become 1.5 times
[B] will become 3 times
[C] will become 2.25 times
[D] will become 6 times
Show Answer
Correct Answer: C [will become 2.25 times]
Notes:
Kinetic Energy is a product of half the Mass times Velocity Squared. When the velocity is doubled, the Kinetic energy would go up four times. If velocity is tripled, kinetic energy would go up nine times. If velocity is increased by 1.5 times the Kinetic energy would go up by 1.5×1.5=2.25 times.
5. Which of the following is the largest practical unit of mass?
[A] Slug
[B] a.m.u
[C] Hyperkg
[D] C.S.L
Show Answer
Correct Answer: D [ C.S.L ]
Notes:
The largest practical unit of mass is called as Chandra Shekhar Limit (C.S.L) which is equivalent to 1.4 times the mass of Sun. Chandrasekhar limit is the maximum mass theoretically possible for a stable white dwarf star. This limiting value was named after Indian-born astrophysicist Subrahmanyan Chandrasekhar, who formulated it in 1930. Using Albert Einstein’s special theory of relativity and the principles of quantum physics, Chandrasekhar showed that it is impossible for a white dwarf star, which is supported solely by a degenerate gas of electrons, to be stable if its mass is greater than 1.44 times the mass of the Sun.
6. Linear momentum can be described in which of the following units?
[A] kgm2/s2
[B] kg/ms2
[C] kg/ms
[D] kgm/s
Show Answer
Correct Answer: D [ kgm/s ]
Notes:
The SI unit of Linear Momentum is kg m/s Linear Momentum = Mass(kg) x Velocity (m/s) Linear Momentum is the quantity of motion of a moving body. Dimensional Formula of Linear Momentum is [M1 L1 T-1]
7. The thrust on the rocket is:
[A] in the same direction of the rocket
[B] in the opposite direction of the rocket
[C] at 90° to the direction of the rocket
[D] None of the above
Show Answer
Correct Answer: B [in the opposite direction of the rocket]
Notes:
The thrust on the rocket is in the opposite direction of the rocket. The thrust is the force with which rocket moves upwards. F = -u (dm/dt)
8. 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.
9. At sea level, what is the difference between the value of acceleration due to gravity at the poles and at the equator?
[A] No difference
[B] 9.8 cm s-2
[C] 1.80 cm s-2
[D] None of the above
Show Answer
Correct Answer: C [1.80 cm s-2]
Notes:
At sea level, the difference between the value of acceleration due to gravity at the poles and at the equator is 1.80 cm s-2. The value of acceleration due to gravity increases as we go from equator to the poles.
10. The ratio of the magnitude of the external force applied on a body to the magnitude of acceleration produced in its motion is known as:
[A] Inertial Mass
[B] Angular Momentum
[C] Gravitational Potential
[D] Gravitational Constant
Show Answer
Correct Answer: A [Inertial Mass]
Notes:
The inertial mass of a body may be measured as the ratio of the magnitude of the external force applied on it to the magnitude of acceleration produced in its motion. It is the measure of ability of the body to oppose the production of acceleration in its motion by an external force.
