In Young's double slit experiment, the width of one of the two slits is four times the width of the other slit. The ratio of the maximum to the minimum intensity in the interference pattern will be
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 9 : 1
The intensity of light from a slit is proportional to its width, and the amplitude is proportional to the square root of the intensity. In the pattern the amplitudes add at a maximum and subtract at a minimum.
\( I_1 : I_2 = 4 : 1 \)
\( a_1 : a_2 = 2 : 1 \quad (\text{square roots of the intensities}) \)
\( \displaystyle \frac{I_{\max}}{I_{\min}} = \frac{(a_1 + a_2)^{2}}{(a_1 - a_2)^{2}} = \frac{(2 + 1)^{2}}{(2 - 1)^{2}} = \frac{9}{1} \)
Note: A similar question was also asked in CUET (UG) 2026 on 24-05-2026 (Slot 2), and in CUET (UG) 2023 on 08-06-2023 (Slot 3) and on 07-06-2023 (Slot 3).