In a biprism experiment, the distance between the first and eleventh fringes formed by light of wavlenght `lambda` is `1.8xx10^(-3)m`. If the ligh is replaced by one of wavelenght `lambda//2`, then distance between the first and sixteenth bright fringe will be

Options

A. `2.35 mm`
B. `1.35 mm`
C. `1.45 mm`
D. `2.45` mm

Answer

B

Explanation

`x_(11b)=11beta_(1)`
`x'_(16b)=16beta_(2)`
`:.beta_(1)=(1.8xx10^(-3))/(11)=1.63xx10^(-4)m=(D)/(d)lamda`
`beta_(2)=(D)/(d)(lamda)/(2)=(1.63xx10^(-4))/(2)=8.15xx10^(-5)m`
`16beta_(2)=16xx8.15xx10^(-5)=1.3040mm`