WBJEE 2024 Physics & Chemistry Paper

In a single-slit diffraction experiment, the position of the diffraction minima is given by the condition:
asin‌θ=nλ
where a is the slit width, θ is the angle of diffraction, n is the order of the minimum, and λ is the wavelength of light.
Let's denote the two wavelengths by λ1 and λ2. According to the problem, the 2‌nd ‌ order diffraction minimum for λ1 coincides with the 3‌rd ‌ order diffraction minimum for λ2. This can be written as:
asin‌θ=2λ1
and

asin‌θ=3λ2
Since both conditions are satisfied simultaneously at the same angle θ, we can equate the two expressions: square
2λ1=3λ2
Thus, the ratio of the wavelengths is:
‌

λ1

λ2

=‌

3

2

Therefore, the correct option is:
Option C: ‌

λ1

λ2

=‌

3

2