In a double-slit experiment, if the wavelength is doubled and the slit…

Question

In a double-slit experiment, if the wavelength is doubled and the slit separation is halved, the fringe width becomes

Accepted Answer

B. {'text': '4 times original', 'label': 'B'}

1. β = λD/d. New wavelength = 2λ; new slit separation = d/2.
2. New β = (2λ)D / (d/2) = 4 × (λD/d) = 4β.
3. So the fringe width becomes 4 times the original.
4. Screen distance D was kept unchanged.
_Source: NCERT Class 12 Physics, Ch 10 "Wave Optics", §10.4_

Answer

{'text': '1/4 of original', 'label': 'A'}

Answer

{'text': '2 times original', 'label': 'C'}

Answer

{'text': 'Same as original', 'label': 'D'}