CBSE Class 12 Physics 2022 Term 2 Outside Delhi Set 1 Solved Paper

Question : 7

Total: 12

In a diffraction pattern due to a single slit, how will the angular width of central maximum change, if
(i) orange light is used in place of green light,
(ii) the screen is moved closer to the slit,
(iii) the slit width is decreased?
Justify your answer in each case. 3

Solution:

The angular width of central maxima of single slit diffraction patten is 2θ=

2λ

(i) Angular width of central maxima ∝ wavelength of light used. Orange light has higher wavelength than that of green light. So, Angular width of central maxima will be more when orange light is used instead of green light.
(ii) Angular width of central maxima is independent of the distance between the slit and the screen. So, if the screen is moved closer to slit there will be no change in angular width of central maxima.
(ii) Angular width of central maxima ∝

slit‌width

So, if the angular width is decreased, the angular width of the central maxima will increase.

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