Chapter 12: Dual Nature of Radiation and Matter — Online MCQ Test
PHYSICS · CLASS 12 INTERMEDIATE 2 YEAR · Telangana State Board
Practice Chapter 12: Dual Nature of Radiation and Matter with a free chapter-wise online MCQ test.
This chapter covers: This chapter details photoelectric effect Hertz Lenard observations Einstein photoelectric equation photon nature and de Broglie matter wave hypothesis..
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter 12: Dual Nature of Radiation and Matter — Important Questions & Answers
Which phenomenon could not be explained by the wave theory of light and led to the discovery of the photoelectric effect?
- A. Interference
- B. Diffraction
- C. Emission of electrons from a metal surface by light
- D. Polarization
Answer: C. Emission of electrons from a metal surface by light
The photoelectric effect is the emission of electrons from a metal surface when light of suitable frequency falls on it. Classical wave theory failed to explain its observed features.
The photoelectric effect is the emission of electrons from a metal surface when light of suitable frequency falls on it. Classical wave theory failed to explain its observed features.
The minimum energy required to remove an electron from a metal surface is called:
- A. Ionization energy
- B. Work function
- C. Threshold energy
- D. Stopping potential
Answer: B. Work function
The work function is the minimum energy needed to liberate an electron from the metal surface. It is usually denoted by ϕ.
The work function is the minimum energy needed to liberate an electron from the metal surface. It is usually denoted by ϕ.
Which of the following observations of the photoelectric effect supports the particle nature of light?
- A. Intensity of light increases the maximum kinetic energy
- B. Photoelectric emission occurs only if frequency is above a certain value
- C. Photoelectric current is independent of intensity
- D. All wavelengths produce emission if intensity is high enough
Answer: B. Photoelectric emission occurs only if frequency is above a certain value
The existence of threshold frequency shows that energy comes in discrete packets. If the light frequency is below the threshold, no electrons are emitted regardless of intensity.
The existence of threshold frequency shows that energy comes in discrete packets. If the light frequency is below the threshold, no electrons are emitted regardless of intensity.
A beam of light of frequency just above threshold falls on a metal plate. If the intensity is doubled, which result is correct?
- A. Maximum kinetic energy doubles
- B. Stopping potential doubles
- C. Photoelectric current increases
- D. Threshold frequency changes
Answer: C. Photoelectric current increases
Doubling intensity increases the number of photons incident per second, hence more electrons are emitted and the current increases. The maximum kinetic energy remains unchanged for the same frequency.
Doubling intensity increases the number of photons incident per second, hence more electrons are emitted and the current increases. The maximum kinetic energy remains unchanged for the same frequency.
A proton and an electron have the same kinetic energy. Which one has the larger de Broglie wavelength?
- A. Proton
- B. Electron
- C. Both have the same wavelength
- D. Cannot be determined
Answer: B. Electron
For the same kinetic energy, momentum is smaller for the lighter particle. Since λ = h/p, the electron has the larger de Broglie wavelength.
For the same kinetic energy, momentum is smaller for the lighter particle. Since λ = h/p, the electron has the larger de Broglie wavelength.