Question

A thin mica sheet of thickness 2 × 10^-6 m and refractive index (µ = 1.5) is introduced in the path of the first wave. The wavelength of the wave used is 5000 Å. The central bright maximum will shift ______.

Options

• 2 fringes upward

• 2 fringes downward 

• 10 fringes upward 

• None of these

Answer 1

A thin mica sheet of thickness 2 × 10^-6 m and refractive index (µ = 1.5) is introduced in the path of the first wave. The wavelength of the wave used is 5000 Å. The central bright maximum will shift 2 fringes upward.

Explanation:

Shift = `beta/lambda (mu - 1)"t"`

`= (beta (1.5 - 1) 2 xx 10^-6)/(5000 xx 10^-10)`

shift = `(beta xx 0.5 xx 2 xx 10^-6)/(5000 xx 10^-10)`

shift = `(beta xx 0.5 xx 2 xx 10^-6)/(5 xx 10^-7)`

shift = 2 β  i.e. 2 fringes upward