A light ray passes from a transparent liquid into a crystal at a non-zero angle to the normal.
The ray bends towards the normal. Its wavelength in the crystal is 0.60 times its wavelength in the liquid.
Measurements of the speed of light in the two substances give two of these values:
| Possible speed |
|---|
| 1.2 × 108 m/s |
| 2.0 × 108 m/s |
| 2.4 × 108 m/s |
Which statement gives the speeds of light in the liquid and in the crystal?
The speed in the liquid is 1.2×108 m/s1.2\times10^8\ \mathrm{m/s}1.2×108 m/s and the speed in the crystal is 2.0×108 m/s2.0\times10^8\ \mathrm{m/s}2.0×108 m/s.
The speed in the liquid is 2.0×108 m/s2.0\times10^8\ \mathrm{m/s}2.0×108 m/s and the speed in the crystal is 2.0×108 m/s2.0\times10^8\ \mathrm{m/s}2.0×108 m/s.
The speed in the liquid is 2.0×108 m/s2.0\times10^8\ \mathrm{m/s}2.0×108 m/s and the speed in the crystal is 1.2×108 m/s1.2\times10^8\ \mathrm{m/s}1.2×108 m/s.
The speed in the liquid is 2.4×108 m/s2.4\times10^8\ \mathrm{m/s}2.4×108 m/s and the speed in the crystal is 1.2×108 m/s1.2\times10^8\ \mathrm{m/s}1.2×108 m/s.
84 exam-style questions on Edexcel GCSE Physics 5.2 The electromagnetic spectrum, covering 5.2.1 Electromagnetic waves and refraction in glass (core practical), 5.2.2 Groups of the electromagnetic spectrum, 5.2.3 Wavelength-dependent behaviour of EM waves, and 5.2.4 Velocities of EM waves in different substances. Each one has a worked solution and a mark scheme showing where the marks go.