The de Broglie wavelength associated with a moving particle is inversely proportional to its: MCQ with Answer and Explanation

The de Broglie wavelength associated with a moving particle is inversely proportional to its:
A. Velocity only
B. Kinetic energy
C. Mass only
D. Momentum
Answer: Option D
Solution (By JKSSB Mock Tests)
Louis de Broglie proposed that matter exhibits wave-like properties. The de Broglie wavelength (lambda) of a particle is given by the formula lambda = h / p, where 'h' is Planck's constant and 'p' is the linear momentum (mass * velocity) of the particle. Therefore, the wavelength is strictly inversely proportional to the momentum of the moving particle.

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Practice More Physics Questions

Question #1
In Young's double slit experiment, if the slit separation is doubled and screen distance halved, the fringe width becomes:
A. Half
B. Double
C. One-fourth
D. Same

Correct Answer: Option C


Explanation:
Fringe width β = λD/d, where λ wavelength, D screen distance, d slit separation. New d' = 2d, new D' = D/2. Thus β' = λ(D/2)/(2d) = λD/(4d) = β/4. Fringe width reduces to one-fourth. Memory tip: 'β ∝ D/d; changes multiply'. This proportional reasoning problem tests wave optics understanding, frequently appearing in competitive exams. Always track how each parameter change affects the result; combine multiplicative factors for net effect. Verify with dimensional analysis: β has length dimension, consistent with λD/d.

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Question #2
The time period of a seconds pendulum is
A. 2 s
B. 4 s
C. 1 s
D. 0.5 s

Correct Answer: Option A


Explanation:
Seconds pendulum has period 2 s (1 s each swing).

This question belongs to: Science Physics
Question #3
The energy emitted by the Sun is primarily a result of:
A. Chemical combustion of gases.
B. Nuclear fusion of hydrogen into helium.
C. Nuclear fission of heavy elements.
D. Radioactive decay of uranium.

Correct Answer: Option B


Explanation:
The Sun and other stars generate their immense energy through nuclear fusion. In the Sun's core, immense gravitational pressure and heat cause hydrogen nuclei (protons) to overcome electrostatic repulsion and fuse together to form helium nuclei. This fusion process releases vast amounts of energy according to Einstein's E=mc².

This question belongs to: Science Physics