Name the parts of the electromagnetic spectrum from radio waves to visible light. Give the wavelength range, the source and one use of each.

1. 1 · Introduce. All EM waves travel at c in vacuum and differ only in wavelength and frequency; c = νλ.
2. 2 · Radio waves. More than 0.1 m; charges accelerated in aerials; radio, TV and mobile phones.
3. 3 · Microwaves. 0.1 m to 1 mm; klystron, magnetron or Gunn diode; radar and microwave ovens.
4. 4 · Infrared. 1 mm to 700 nm; hot bodies and vibrating molecules; TV remotes, physiotherapy, the greenhouse effect.
5. 5 · Visible light. 700 nm to 400 nm; electrons in atoms moving to lower levels; vision and photography.
6. 6 · Real life. Satellites study crop growth using infrared.
7. 7 · Close in one line. So, going from radio to visible, the wavelength falls and the frequency rises.

Scoring tip: Write every range with its unit (m, mm, nm); a range without a unit gets no mark.