If the distance between the first maxima and fifth minima of a double-slit pattern is 7 mm and the slits are separated by 0.15 mm with the screen 50 cm from the slits, then wavelength of the light used is

Options

A. 600 nm
B. 525 nm
C. 467 nm
D. 420 nm

Answer

A

Explanation

For minima `y_(n)=(2n-1)(lamdaD)/(2d)`
where n is the no. of minimum
For maxima `y_(n)=(nlamdaD)/(d)`
`y_(5^(th)"dard")=(9lamdaD)/(2d):y_(1^(@)" maxima")=(lamdaD)/(d)`
By equation `y_(5^(@)" min")-y_(1^(@)" max")=7xx10^(-3)`
`(9lamdaD)/(2d)-(lamdaD)/(2d)=7xx10^(-3)implieslamda=(7xx10^(-3)xx15xx10^(-5)xx2)/(7xx50xx10^(-2))`
`thereforelamda=600nm`