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The Photoelectric Effect

Part of the Optics, Waves and Modern Physics section of Coddy's Physics journey. Lesson 35 of 53.

Light on a metal frees electrons: the photoelectric effect.

A phototube

Below the threshold frequency: no electrons, however bright. Brighter: more electrons. Higher f: faster ones.

One photon frees one electron. It needs at least the work function W: hf₀ = W.

Challenge

Sodium has a work function of 2.3 eV. What is its threshold frequency f_0?

Try it yourself

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Optics, Waves and Modern Physics

1Reflection and Refraction

Reflection of Light The Refractive Index Snell's Law Total Internal Reflection Dispersion Apparent Depth Recap - Optical Fiber

4Mechanical Waves

What a Wave Is Two Graphs of a Wave When Pulses Meet Interference Standing Waves Harmonics Recap - Guitar String

7Photons

Light Comes in PhotonsThe Photoelectric EffectEinstein's Equation Stopping Voltage Counting Photons Recap - Solar Cell

10Nuclear Energy

Mass Defect Binding Energy per Nucleon Fission and Fusion Recap - Inside the Sun

2Plane Mirrors

The Image in a Mirror Seeing in a Mirror Two Mirrors Recap - Periscope

5The Ripple Tank

Two Sources Nodal Lines How the Pattern Changes Recap - Two Speakers

8The Bohr Atom

The Bohr Model Emission and Absorption Spectral Lines Recap - Hydrogen Lamp

3Thin Lenses

Lenses and Their Rays The Lens Equation Virtual Images Two Lenses A Lens and a Mirror Recap - Build a Projector

6Light as a Wave

Light Through Two Slits Fringes on a Screen Diffraction by One Slit The Diffraction Grating Recap - Measure with a CD

9The Nucleus

Inside the Nucleus Radioactive Decay Half-Life Activity Radioactive Dating Recap - Carbon Dating