Answer :
Answer:
t = 37 x 10⁻⁶ m
Explanation:
given,
Length of glass plate,L = 9.47 cm
wavelength of the light, λ = 585 nm
Number of bands, n = 127 bands
thickness of the hair, t = ?
When the light get refracted from the inner surface of glass the wavelength of the light does not changes.
But when the light is refracted from the outer surface there is a dark band which shows that the wavelength changes.
now,
For the first order of bright band has phase difference = λ/2
for nth order
[tex]p = (2n-1)\dfrac{\lambda}{2}[/tex]
p = 2 t
[tex]2t= (2n-1)\dfrac{\lambda}{2}[/tex]
[tex]2\times t= (2\times 127-1)\times dfrac{585\times 10^{-9}}{2}[/tex]
t = 37 x 10⁻⁶ m
Hence the thickness of the hair is equal to t = 37 x 10⁻⁶ m