A ray of light travelling in air strikes a block of acrylic plastic at an angle of 40∘40^\circ40∘ to the normal. The light slows down as it enters the plastic block.
State and explain, in terms of wavefronts, what happens to the light.
The speed of light in this acrylic plastic block is 2.1×108 m/s2.1 \times 10^8\text{ m/s}2.1×108 m/s. The speed of light in vacuum (or air) is 3.0×108 m/s3.0 \times 10^8\text{ m/s}3.0×108 m/s.
Calculate the refractive index of the acrylic plastic.
100 exam-style questions on CIE IGCSE Physics 3.2.2 Refraction of light. Each one has a worked solution and a mark scheme showing where the marks go.