---

Question 1:

What is the photoelectric effect?

A) The emission of light by excited atoms
B) The scattering of light by small particles
C) The absorption of light by a material
D) The ejection of electrons by light

Show Answer

Explanation: The correct answer is D) The ejection of electrons by light. The photoelectric effect refers to the phenomenon where light of sufficiently high frequency (energy) can eject electrons from a material. It provided evidence for the particle-like behavior of light and led to the development of quantum theory.

---

Question 2:

According to the photoelectric effect, the kinetic energy of emitted electrons depends on:

A) The intensity of light
B) The wavelength of light
C) The speed of light
D) The frequency of light

Show Answer

Explanation: The correct answer is D) The frequency of light. According to the photoelectric effect, the kinetic energy of emitted electrons depends on the frequency (energy) of the incident light. Higher-frequency light (shorter wavelength) corresponds to higher energy, resulting in more energetic electrons being emitted.

---

Question 3:

Which phenomenon observed in the photoelectric effect cannot be explained by classical wave theory?

A) Emission of electrons
B) Conservation of energy
C) Dependence on light intensity
D) Threshold frequency

Show Answer

Explanation: The correct answer is C) Dependence on light intensity. The dependence of the photoelectric effect on light intensity cannot be explained by classical wave theory. According to classical wave theory, increasing the intensity (brightness) of light should result in more electrons being emitted, regardless of the frequency. However, the photoelectric effect shows that only light above a certain threshold frequency can cause electron emission, and the number of emitted electrons depends on the intensity once the threshold is exceeded.

---

Question 4:

The energy of a photon is directly proportional to its:

A) Speed
B) Wavelength
C) Intensity
D) Frequency

Show Answer

Explanation: The correct answer is D) Frequency. The energy of a photon is directly proportional to its frequency. According to quantum theory, the energy of a photon is given by E = hf, where E represents energy, h is Planck's constant, and f is the frequency of the photon. Higher frequency photons carry higher energy.

---

Question 5:

Which scientist's work on the photoelectric effect contributed significantly to the development of quantum theory?

A) Isaac Newton
B) Max Planck
C) Albert Einstein
D) Erwin Schrödinger

Show Answer

Explanation: The correct answer is C) Albert Einstein. Albert Einstein's work on the photoelectric effect made significant contributions to the development of quantum theory. His explanation of the photoelectric effect, which involved the concept of photons as discrete energy packets, helped establish the particle-like nature of light and laid the foundation for the quantum theory of light.