If two slits have width ratio 1 : 4. The ratio of maximum to minimum intensities in the interference pattern would 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 intensity is proportional to the square of the amplitude. The resultant intensity ranges between \( I_{\max}\propto(a_1+a_2)^{2} \) and \( I_{\min}\propto(a_1-a_2)^{2} \).
\( \displaystyle \frac{I_1}{I_2} = \frac{1}{4} \Rightarrow \frac{a_1}{a_2} = \frac{1}{2} \)
\( \displaystyle \frac{I_{\max}}{I_{\min}} = \frac{(a_1+a_2)^{2}}{(a_1-a_2)^{2}} = \frac{(1+2)^{2}}{(2-1)^{2}} = \frac{9}{1} \)
Note: A similar question was also asked in CUET (UG) 2026 on 24-05-2026 (Slot 2), in CUET (UG) 2025 on 22-05-2025 (Slot 1), and in CUET (UG) 2023 on 07-06-2023 (Slot 3).