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QJEEM22Pha20f: JEE Main 2022 Physics - Class 11 JEEM22Pha20f Solution: A travelling microscope is used to determine the refractive…

A travelling microscope is used to determine the refractive index of a glass slab. If 40 divisions are there in 1 cm on main scale and 50 Vernier scale divisions are equal to 49 main scale divisions, then least count of the travelling microscope is __________ ×\times 10 −- 6 m.

Step-by-Step Verified Solution

40 M = 1 cm

⇒\Rightarrow M = 0.025 cm .......... (1)

Also, 50 V = 49 M

⇒\Rightarrow Least count = M −- V = M −- 4950{{49} \over {50}} M = M50{{M} \over {50}}

⇒\Rightarrow LC = 0.02550{{0.025} \over {50}} cm

= 25050{{250} \over {50}} ×\times 10 −- 6 m

⇒\Rightarrow LC = 5 ×\times 10 −- 6 m

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