physics : class12 Einstein's Explanation : Particle Nature of Light : Dual Nature of Matter and Radiation MCQ Questions and Answers
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Einstein's Explanation
MCQ questions and answers.
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MCQ Questions
1. According to Einstein's explanation of the photoelectric effect, light consists of discrete packets of energy called:
A.
Electrons
B.
Photons
C.
Protons
D.
Neutrons
Correct Answer:
Photons
Explanation:
Einstein proposed that light energy is concentrated in discrete packets called photons.
2. The energy of a photon according to Einstein is given by:
A.
E = mc²
B.
E = hν
C.
E = mv
D.
E = h/ν
Correct Answer:
E = hν
Explanation:
Einstein stated that the energy of each photon is proportional to the frequency of radiation, with E = hν.
3. In Einstein's photon theory, the energy of a photon depends directly on the:
A.
Amplitude of light
B.
Frequency of light
C.
Speed of light only
D.
Distance from the source
Correct Answer:
Frequency of light
Explanation:
The photon energy is E = hν, so it increases directly with the frequency of light.
4. According to Einstein's explanation, one photon transfers its energy to:
A.
One electron
B.
All electrons in the metal
C.
Only the nucleus
D.
The entire metal plate equally
Correct Answer:
One electron
Explanation:
Einstein considered photoelectric emission as a one-to-one interaction in which one photon transfers its energy to one electron.
5. The minimum energy required to remove an electron from a metal surface is called its:
A.
Kinetic energy
B.
Work function
C.
Photon energy
D.
Rest energy
Correct Answer:
Work function
Explanation:
Einstein's photoelectric equation includes the work function, which is the minimum energy needed to liberate an electron from the metal.
6. Einstein's photoelectric equation is:
A.
hν = φ + Kmax
B.
hν = φ - Kmax
C.
φ = hν + Kmax
D.
Kmax = φ - hν
Correct Answer:
hν = φ + Kmax
Explanation:
The photon energy is used partly to overcome the work function and the remainder appears as the maximum kinetic energy of the emitted electron.
7. If the frequency of incident light is below the threshold frequency, Einstein's explanation predicts that photoelectric emission will:
A.
Occur with lower kinetic energy
B.
Not occur
C.
Occur only at high intensity
D.
Produce more electrons
Correct Answer:
Not occur
Explanation:
A photon must have at least the work-function energy. Below the threshold frequency, its energy is insufficient to eject an electron.
8. According to Einstein's explanation, increasing the intensity of light of frequency above the threshold mainly increases the:
A.
Energy of each photon
B.
Number of photons incident per second
C.
Frequency of each photon
D.
Work function of the metal
Correct Answer:
Number of photons incident per second
Explanation:
For a fixed frequency, increasing intensity increases the number of photons arriving per second, while the energy of each photon remains unchanged.
9. According to Einstein's photon theory, the maximum kinetic energy of photoelectrons is determined by the:
A.
Frequency of incident light
B.
Intensity of incident light only
C.
Size of the metal plate
D.
Duration of illumination
Correct Answer:
Frequency of incident light
Explanation:
From Kmax = hν - φ, the maximum kinetic energy depends on the frequency of light and the work function of the metal.
10. Einstein's explanation accounts for the immediate emission of photoelectrons because:
A.
Electrons slowly absorb energy from many waves
B.
A photon transfers its energy in a single interaction
C.
The metal heats up before emission
D.
The light travels faster near the metal
Correct Answer:
A photon transfers its energy in a single interaction
Explanation:
In Einstein's model, an electron receives the required photon energy in one interaction, so emission can occur without a measurable time delay.
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