Chapter-11 Dual Nature of Radiation and Matter — Online MCQ Test
PHYSICS · Grade 12 · CBSE(NCERT)
Practice Chapter-11 Dual Nature of Radiation and Matter with a free chapter-wise online MCQ test.
This chapter covers: photoelectric effect - Einstein equation - de Broglie wavelength - particle nature of light.
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter-11 Dual Nature of Radiation and Matter — Important Questions & Answers
What is the minimum energy required to remove an electron from a metal surface called?
- A. Ionization energy
- B. Work function
- C. Binding energy
- D. Threshold energy
Answer: B. Work function
Work function (W) is the minimum energy needed to eject an electron from a metal surface in the photoelectric effect.
Work function (W) is the minimum energy needed to eject an electron from a metal surface in the photoelectric effect.
The photoelectric effect cannot be explained by which of the following classical theories?
- A. Wave theory of light
- B. Particle theory of light
- C. Corpuscular theory of light
- D. Quantum theory of light
Answer: A. Wave theory of light
The wave theory of light fails to explain why increasing intensity (amplitude) doesn't increase maximum kinetic energy of ejected electrons.
The wave theory of light fails to explain why increasing intensity (amplitude) doesn't increase maximum kinetic energy of ejected electrons.
A photon with energy E has a momentum of ___?
- A. E/c
- B. Ec
- C. E√c
- D. E/c²
Answer: A. E/c
For a photon, E = hν and p = h/λ = hν/c = E/c, where c is the speed of light.
For a photon, E = hν and p = h/λ = hν/c = E/c, where c is the speed of light.
Compare the de Broglie wavelengths of an electron and a proton, both moving with the same kinetic energy. Which has a longer wavelength?
- A. Electron
- B. Proton
- C. Both have equal wavelength
- D. Cannot be determined
Answer: A. Electron
Since λ = h/√(2mKE), for same KE, the particle with smaller mass (electron) has larger wavelength.
Since λ = h/√(2mKE), for same KE, the particle with smaller mass (electron) has larger wavelength.
An alpha particle (mass = 4u) and an electron (mass = 1u) have the same kinetic energy. Which has a longer de Broglie wavelength?
- A. Alpha particle
- B. Electron
- C. Both have equal wavelength
- D. Depends on the kinetic energy value
Answer: B. Electron
λ = h/√(2mKE); with same KE, particle with smaller mass (electron) has longer wavelength.
λ = h/√(2mKE); with same KE, particle with smaller mass (electron) has longer wavelength.