JEE MAIN - Physics (2021 - 27th July Evening Shift - No. 20)
The difference in the number of waves when yellow light propagates through air and vacuum columns of the same thickness is one. The thickness of the air column is ___________ mm. [Refractive index of air = 1.0003, wavelength of yellow light in vacuum = 6000 $$\mathop A\limits^o $$]
Answer
2
Explanation
Thickness t = n$$\lambda$$
So, n $$\lambda$$vac = (n + 1) $$\lambda$$air
n $$\lambda$$ = (n + 1) $${\lambda \over {{\mu _{air}}}}$$
n = $${1 \over {{\mu _{air}} - 1}} = {{{{10}^4}} \over 3}$$
t = n$$\lambda$$
$$ = {{{{10}^4}} \over 3} \times 6000\mathop A\limits^o $$
= 2 mm
So, n $$\lambda$$vac = (n + 1) $$\lambda$$air
n $$\lambda$$ = (n + 1) $${\lambda \over {{\mu _{air}}}}$$
n = $${1 \over {{\mu _{air}} - 1}} = {{{{10}^4}} \over 3}$$
t = n$$\lambda$$
$$ = {{{{10}^4}} \over 3} \times 6000\mathop A\limits^o $$
= 2 mm
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