(b)

(i) To calculate the angle of refraction:

List the known quantities:

Recall the equation linking refractive index with angles of incidence and refraction:

Rearrange to make sin r the subject:

Calculate to find sin r :

Use sin⁻¹ to find the value of r :

Round the answer to two significant figures and include the units

(ii) To determine wavelength:

List the known quantities:

Recall the equation linking refractive index with speed in a more dense medium:

$n = \frac{v_{a}}{v_{g}}$ where v_a is the speed in the air and v_g is the speed in the glass prism; [1 mark]

Rearrange to make the speed in the solid the subject:

Calculate the speed in the solid:

Recall the wave equation;

Rearrange to make wavelength the subject:

Substitute the values and calculate:

$λ = \frac{2.3 \times 10^{8}}{5.7 \times 10^{14}} = 4.0 \times 10^{- 7}$ m [1 mark]

[Total: 6 marks]

General Properties of Waves (CIE IGCSE Physics: Co-ordinated Sciences (Double Award))

Exam Questions