Photoelectric effect

What does the term quantum mean?

 A quantum is a discrete amount of energy. It refers to the smallest possible unit of energy that can be emitted or absorbed, as introduced by Max Planck.

What did Einstein’s explanation of the photoelectric effect demonstrate?

It showed that light consists of particles called photons, and each photon has energy proportional to its frequency. This explained why light of different frequencies affects electrons differently.

 What happens in the instantaneous ejection of electrons?

Electrons are ejected immediately when light is turned on, even if the light source is weak. This suggests that the energy transfer from the photon to the electron is instantaneous and does not require time to build up.

How does frequency affect the photoelectric effect?

Frequency Dependence: Violet or ultraviolet light easily ejects electrons, while red light does not, regardless of its intensity. This means higher frequency light has more energy per photon.

 How does brightness affect the photoelectric effect?

Brightness Affects Quantity, Not Energy: The rate of ejected electrons depends on the brightness of the light (more photons mean more electrons ejected), but the energy of the ejected electrons is not influenced by brightness.

How does frequency influence the energy of ejected electrons?

Energy Depends on Frequency: The maximum energy of ejected electrons increases with the light’s frequency, not its brightness. Higher frequency light means higher energy photons and therefore more energetic ejected electrons.

What is the work function in the photoelectric effect?

The work function is the minimum energy needed to eject an electron from a material. If a photon’s energy is less than this work function, no electrons will be ejected, regardless of the light’s intensity.

What is the significance of the threshold frequency?

The threshold frequency is the minimum frequency required for light to eject electrons from a material. If the frequency of light is below this threshold, no electrons are ejected, regardless of intensity.

 How did the classical theory of light fail to explain the photoelectric effect?

Classical theory predicted that the energy of ejected electrons should depend on the intensity of light, and there should be a time delay in electron ejection. However, experiments showed that electron energy depends on frequency, not intensity, and there is no time delay.

Why is the photoelectric effect important in quantum physics

It demonstrates that light has particle-like properties and energy is quantized, leading to the concept of photons. This dual nature of light (wave and particle) is a key concept in quantum mechanics.