Physics tough MCQs

By: Prof. Dr. Fazal Rehman | Last updated: May 20, 2025

1. In quantum mechanics, the Heisenberg uncertainty principle implies that:
(A) Energy and mass are interchangeable
(B) The speed of light is constant
(C) The more precisely the position is known, the less precisely the momentum is known
(D) Particles have fixed orbits

2. What is the dimension of Planck’s constant (h)?
(A) ML²T⁻²
(B) ML²T⁻¹
(C) MLT⁻²
(D) ML⁻¹T

3. Which of the following electromagnetic waves has the shortest wavelength?
(A) Infrared rays
(B) Microwaves
(C) X-rays
(D) Ultraviolet rays

4. Which of the following is not a valid consequence of Einstein’s theory of relativity?
(A) Time dilation
(B) Length contraction
(C) Mass increase at high speeds
(D) Conservation of charge

5. Bernoulli’s equation is valid only when:
(A) The flow is rotational
(B) Viscosity is dominant
(C) Flow is compressible
(D) Flow is steady and inviscid

6. The Lagrangian of a system is defined as:
(A) Kinetic Energy – Potential Energy
(B) Potential Energy – Kinetic Energy
(C) Total Energy
(D) Work done

7. A blackbody is an ideal object that:
(A) Reflects all radiation
(B) Absorbs and emits radiation perfectly
(C) Emits only in the visible spectrum
(D) Does not emit radiation

8. Which particle has zero rest mass?
(A) Proton
(B) Neutron
(C) Photon
(D) Electron

9. In nuclear physics, binding energy per nucleon generally:
(A) Decreases with increasing atomic number
(B) Increases with increasing atomic number
(C) Remains constant
(D) First increases, then decreases

10. In Bohr’s atomic model, electrons revolve around the nucleus in:
(A) Random orbits
(B) Elliptical orbits
(C) Quantized circular orbits
(D) Spiral paths