A light wave is incident normally over a slit of width `24xx10^-5cm`. The angular position of second dark fringe from the central maxima is `30^@`. What is the wavelength of light?

Options

A. 6000 Å
B. 5000 Å
C. 3000 Å
D. 1500 Å

Answer

A

Explanation

For the nth minima in the diffraction pattern on the screen, the path difference, `asintheta=nlamda`
for the angular position of the nth minima, `sintheta=(nlamda)/(a)`
`therefore lamda=(asintheta)/(n)=(asin30^(@))/(2)`
`=(24xx10^(-5)xx10^(-2)xx(1)/(2))/(2)`
`therefore lamda=6xx10^(-7)=6000` Å