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GCSE Questions - Electromagnetic Spectrum

Q4. A laser emits light waves in the visible region of the electromagnetic spectrum.

(a) What type of wave are all electromagnetic waves?

They are all transverse waves.

[1 mark]

(b) The light from a laser has a wavelength of 6.5 x 10-7 m The speed of light is 3.0 x 108 m/s

Calculate the frequency of the light from the laser. Give your answer to 2 significant figures.

speed (m/s) = frequency (Hz) x wavelength (m)

frequency (Hz) = speed (m/s) /wavelength (m)

= 3.0 x 108 m/s / 6.5 x 10-7 m

= 3.0/6.5 x 1015 Hz

= 4.6 (2 sig figs) x 1014 Hz

[4 marks]

(c) What is the approximate range of wavelengths of the electromagnetic spectrum? Tick one box.

Range of wavelengths in metres
 Tick
10-10 to 108
  
10-8 to 106
  
10-15 to 104

You need to know not only the names of the parts of the electromagnetic spectrum, but also their general properties as well. You have to recall them!

This page in my site summarises what you should know....

[1 mark]

(Total 6 marks)