Question

In the biprism experiment, fringes are obtained using monochromatic light. The distance between the 5^th bright band and 9^th dark band on the same side of the central bright band, in terms of the fringe width 'X' is ______

Options

• 3 X

• 3.5 X

• 4 X

• 4.5 X

Answer 1

In the biprism experiment, fringes are obtained using monochromatic light. The distance between the 5^th bright band and 9^th dark band on the same side of the central bright band, in terms of the fringe width 'X' is 3.5 X.

Explanation:

`y_5 = (5lambdaD)/d`

`y_9^' = (17lambdaD)/(2d)`

X = `(lambdaD)/d`

∴ y₅ = 5X

`y_9^'= 17/2`X

∴ `|y_5 - y_9^'| = X|(5 - 17/2)| = X7/2 = 3.5`X