The question asks for the definition of the photoelectric effect. We need to recall the fundamental principles of this phenomenon, which involves the interaction of light with matter, specifically the emission of electrons from a metal surface.
A) Electrons are emitted from the surface of a metal when light of sufficiently high frequency falls upon it. This statement accurately describes the photoelectric effect. The phrase "sufficiently high frequency" directly refers to the threshold frequency requirement. If the frequency is below this threshold, no electrons are emitted, irrespective of the light's intensity. This aligns perfectly with the quantum nature of light and the energy required to overcome the work function of the metal.
The question asks about the fundamental concept from Max Planck's work that Albert Einstein used to explain the photoelectric effect. This requires recalling the historical development of quantum theory and Einstein's specific contribution to understanding light.
A) The quantum (particle) nature of light, with light energy existing in discrete packets called photons — This accurately describes Einstein's revolutionary idea, directly building on Planck's quantum hypothesis, to explain the photoelectric effect. He proposed that light itself is quantized into particles (photons) with energy \(E = h\nu\).
The question asks for Einstein's Photoelectric Equation, which describes the maximum kinetic energy of emitted photoelectrons. This equation is based on the principle of conservation of energy applied to the photoelectric effect.
D) KE_max = hf - φ
The question asks for the definition of 'work function' in the context of the photoelectric effect. This is a fundamental concept in modern physics, specifically related to the interaction of light with matter.
Correct Option: C) The minimum energy required to remove an electron from the surface of the metal
This option accurately defines the work function. It represents the energy barrier that an electron must overcome to escape the metallic surface.
The question asks for the definition of 'threshold frequency' in the context of the photoelectric effect. This is a fundamental concept in quantum physics, specifically related to how light interacts with matter to eject electrons.
C) The minimum frequency of incident light below which no photoelectric emission can occur, regardless of light intensity. This accurately defines the threshold frequency. If the frequency of light is below this threshold, individual photons do not have enough energy to overcome the work function of the metal, and thus no electrons are ejected.
The photoelectric effect describes the emission of electrons when light shines on a material. Its characteristics are crucial for understanding quantum physics. This question tests the understanding of how the intensity of incident light affects the emitted photoelectrons, specifically their number and kinetic energy, while keeping the frequency constant and above the threshold.
B) An increase in the number of photoelectrons emitted per second (and hence photoelectric current), but no change in their maximum kinetic energy. This aligns with the principles of the photoelectric effect: higher intensity means more photons, leading to more emitted electrons, but the energy of each emitted electron (and thus its maximum kinetic energy) depends only on the frequency of the incident light and the material's work function.