Cambridge A Level Physics AS Diffraction Grating Equation Questions

[Maximum number: 6]

(a)

A diffraction grating is used to determine the wavelength of light.

[ 3 ]

(i)

By reference to interference, explain

[ 3 ]

1. waves (from each element/slit) overlap/meet/superpose

with a phase difference/path difference of zero

2. phase difference is $360^{\circ}$ / path difference of $\lambda$

(i)

the zero order maximum,

(ii)

the first order maximum.

[ 3 ]

(b)

A diffraction grating is used with different wavelengths of light. The angle $\theta$ of the second order maximum is measured for each wavelength. The variation with wavelength $\lambda$ of $\sin \theta$ is shown in Fig. 5.1.

Fig. 5.1

[ 3 ]

(i)

Use the gradient determined in (i) to calculate the slit separation d of the diffraction grating.

[ 2 ]

$d \sin \theta=n \lambda$

d=n / gradient
$=2 / 8.0 \times 10^{5}=2.5 \times 10^{-6} \mathrm{~m}$

(ii)

On Fig. 5.1, sketch a line to show the results that would be obtained for the first order maxima.

[ 1 ]

straight line drawn with lower gradient (about $\frac{1}{2}$ ) and all points lower

CAIE A-Level Physics AS 8.4.1 D Sin N Questions

Exam points

CAIE A-Level Physics AS 8.4.1 D Sin N Questions question 1

Question (a)

Question (i)

Question (i)

Question (ii)

Question (b)

Question (i)

Question (ii)