Two wavelengths of light `lambda_(1)` and `lambda_(2)` and sent through Young's double-slit apparatus simultaneously. If the third-order bright fringe coincides with the fourth-order bright fringe, then

Options

A. `(lambda_(1))/(lambda_(2)) = (4)/(3)`
B. `(lambda_(1))/(lambda_(2)) = (3)/(4)`
C. `(lambda_(1))/(lambda_(2)) = (5)/(4)`
D. `(lambda_(1))/(lambda_(2)) = (4)/(5)`

Answer

a

Explanation

`y_(1) = 3 ((lambda_(1) D)/(d))` and `y_(2) = 4 ((lambda_(2) D)/(d))`
Since both fall at the same location, so
`y_(1) = y_(2)`
`(lambda_(1))/(lambda_(2)) = (4)/(3)`