A diffraction grating is illuminated with yellow light at normal incidence. The pattern seen on a screen behind the grating consists of three yellow spots, one at zero degrees (straight through) and one each at ±45°. You now add red light of equal intensity, coming in the same direction as the yellow light. The new pattern consists of1. red spots at 0 and + / - 45

2. yellow spots at 0 and + / - 45

3. Orange spots at 0 and + / - 45

4. an orange spot at 0, yellow spots at + / - 45, and red spots slightly further out

5. an orange spot at 0, yellow spots at + / - 45, and red spots slightly closer in

Question

Charlize Walls

Physics

29 July, 14:31

A diffraction grating is illuminated with yellow light at normal incidence. The pattern seen on a screen behind the grating consists of three yellow spots, one at zero degrees (straight through) and one each at ±45°. You now add red light of equal intensity, coming in the same direction as the yellow light. The new pattern consists of1. red spots at 0 and + / - 45

2. yellow spots at 0 and + / - 45

3. Orange spots at 0 and + / - 45

4. an orange spot at 0, yellow spots at + / - 45, and red spots slightly further out

5. an orange spot at 0, yellow spots at + / - 45, and red spots slightly closer in

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Answers (1)

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Isabell Johnston · Answer 1

4. an orange spot at 0, yellow spots at + / - 45, and red spots slightly further out

Explanation:

At central place (zero degree) central maxima of both the color will be formed resulting into formation of orange spot there. At + / - 45 degree, yellow spot will be formed as before. For red light, wave length is larger so fringe width will be greater. Hence fringe will be formed farther away from the region of central maxima. It means red spot will be observed farther away or out.