Question

What happens to the fringe pattern when the youngs double slit experiment is performed in water instead of air

Answer 1

a) Slit separation is increased so spacing decreases.

b) Light wavelength is decreased so spacing decreases. With a single slit the spacing increases with wavelength, though if you reduce the width of the slit enough, the number of fringes decreases and their size increases.

Answer 2

Answer:

The Correct Answer would be decrement of fringe width. When the Young's Double-Slit Experiment is performed in water instead of air, then decrement in fringe width can be observed.

Explanation:

For the Young's double-slit experiment, the fringe width is given as:

β= $\frac{Dk.}{d}$                                            (eq. 1)

Now, we can conclude that fringe width(β) here is directly proportional to the wavelength(k) of the light wave, i.e., β∝k.

Now, from the formula c = kv, we can see that wavelength(k) ∝ speed of light(c). As speed of light decreases in water (becomes 2×10⁸ m/s), the wavelength of wave, being directly proportional to c also decreases.

Hence, from eq. 1, β should also decrease as β∝k.

Hence, Fringe Width deceases in water.