The speed of light in air is 3.0 × 108 m/s. The critical angle for light in a type of optical glass placed in air is 42∘42^\circ42∘. What is the speed of light in this optical glass?
1.5×108 m/s1.5 \times 10^8\text{ m/s}1.5×108 m/s
2.0×108 m/s2.0 \times 10^8\text{ m/s}2.0×108 m/s
3.0×108 m/s3.0 \times 10^8\text{ m/s}3.0×108 m/s
4.5×108 m/s4.5 \times 10^8\text{ m/s}4.5×108 m/s
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.