The photoelectric effect demonstrated that:
Show answer & explanation
Correct answer: C
Explanation
Solution: The correct answer is Light energy is quantized and delivered in discrete packets, confirming the particle nature of light.
Explanation:
☛ The photoelectric effect is the phenomenon in which electrons are ejected from the surface of a metal when light of a suitable frequency falls on it.
☛ Classical wave theory failed to explain why emission occurs instantaneously and why electron energy depends on frequency rather than light intensity.
☛ In 1905, Albert Einstein successfully explained this effect by applying Max Planck’s quantum hypothesis, proving that light travels as discrete packets of energy called photons.
☛ Each photon carries an energy of E = hν (where h is Planck's constant and ν is frequency), which established the particle nature of light.
☛ For this revolutionary explanation, Albert Einstein was awarded the Nobel Prize in Physics in 1921.
Extra Exam-Relevant Facts:
☛ Threshold Frequency (ν₀): The minimum frequency of incident light below which no photoelectrons can be ejected, regardless of the light's intensity.
☛ Work Function (Φ): The minimum energy required to liberate an electron from the metal surface, given by Φ = hν₀.
☛ Effect of Intensity: The rate of photoelectron emission (photocurrent) is directly proportional to the intensity of incident light.
☛ Effect of Frequency: The maximum kinetic energy of the emitted photoelectrons depends linearly on the frequency of the incident radiation.
☛ Thermionic Emission: The release of electrons from a metal surface by heating it, which is distinct from the photoelectric effect.
Important One-Liners for Upcoming Exams:
☛ Who discovered the photoelectric effect experimentally in 1887? → Heinrich Hertz
☛ What is a discrete packet or quantum of light energy called? → Photon
☛ What is the value of Planck's constant (h)? → 6.626 × 10⁻³⁴ J·s
☛ What is the minimum energy required to release an electron from a metal surface? → Work Function
☛ On which property of incident light does the maximum kinetic energy of photoelectrons depend? → Frequency