1.

A plane light wave falls on Fresnel mirrors at an inclination of alpha = 2. Detrmine the wavelength of light if the width of fringe on the screen is beta = 0.55 m:

Answer»

220 nm
330 nm
640 nm
750 nm

Solution :`beta = (lambda(1 + (B)/(r))/(2a))`
As wave is plane wavefront, `r = infty`
`THEREFORE beta = (lambda)/(2a)`
`therefore lambda = 2 ALPHA beta = (2 xx 2PI)/(180 xx 60) xx 0.55 xx 10^(-3)`
` = 640 nm`.


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