Physics › Section R · Electromagnetic waves and geometric optics › Topic R.1
Maxwell's equations and making EM waves
Radio, light and X-rays look nothing alike, yet they are the same thing: electric and magnetic fields regenerating each other as they race through space. James Clerk Maxwell predicted these waves from four laws of electricity and magnetism, and even worked out their speed, before anyone knew that light was one of them.
In this topic
- A wave predicted on paper
- Maxwell's equations in words
- The missing piece: a changing electric field
- The speed of the wave
- Worked example: the speed of light from two constants
- Hertz makes and detects the waves
- How an antenna makes a wave
- The shape of the wave and E = cB
- Worked example: the magnetic field of a radio wave
- Worked example: sizing a half-wave antenna
- Common mistakes to avoid
- Key takeaways
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