The photoelectric effect Flashcards – AQA A-level Physics (7408)

What is the photoelectric effect?

The emission of electrons from a material when it absorbs electromagnetic radiation.

What is the energy of a photon of frequency $f$?

$E = hf$, where $h$ is the Planck constant.

In the photon model, from what does an electron absorb energy?

An individual photon.

What is a material’s work function?

The minimum energy needed to release an electron from the material.

What is the threshold frequency for photoelectric emission?

The lowest radiation frequency that can cause photoelectric emission.

What equation relates the work function $\phi$ to the threshold frequency $f_0$?

$hf_0 = \phi$

Why can radiation below the threshold frequency not cause photoelectric emission, regardless of its intensity?

Each photon has insufficient energy to release an electron.

How does the material affect the work function and threshold frequency?

Both depend on the material.

What is the photoelectric energy equation?

$hf = \phi + E_{k\,(\max)}$ Photon energy equals the work function plus the maximum photoelectron kinetic energy.

What does the maximum kinetic energy in the photoelectric equation describe?

The kinetic energy of the most energetic escaping photoelectrons; other emitted electrons can have less.

What is the stopping potential in the photoelectric effect?

A potential difference opposing photoelectrons that is just sufficient to prevent even the most energetic from reaching the collector.

How is the magnitude of the stopping potential related to the maximum photoelectron kinetic energy?

$E_{k\,(\max)} = eV_s$ Here, $e$ is the magnitude of the electron charge and $V_s$ is the stopping-potential magnitude.