In Young's double slit experiment, 62 fringes are seen in visible region for sodium light of wavelength 5893 Å. If violet light of wavelength 4359 Å is used in place of sodium light, then what is the number of fringes seen?

Explanation

From young.s double slit expriment
`(n_(1)lambda_(1)D)/(d)=(n_(2)lambda_(2)D)/(d)`
`lambda_(1) = 5893Å , lambda_(2) = 4359 Å`
`n_(1) = 62 , n_(2) = ?`
The above condition is total extent of fringes is constant for both wavelenghts
`(62xx5893xx10^(-10)xxD)/(d)=(n_(2)xx4359xx10^(-10)xxD)/(d)`
`n_(2)=(62xx5893)/(4359)=(365366)/(4359)=83.8`
`n_(2) = 84`