JEE Main · 2024 · 06 Apr 2024 · Shift 1 · Units & Measurement

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While measuring diameter of wire using screw gauge the following readings were noted. Main scale reading is 1 mm and circular scale reading is equal to 42 divisions. Pitch of screw gauge is 1 mm and it has 100 divisions on circular scale. The diameter of the wire is

\frac{x}{50} mm

. The value of

x

is :

(A)142
(B)71✓ Correct
(C)42
(D)21

Answer: (B)

Solution

Least count

= \frac{pitch}{no. of circular divisions} = \frac{1}{100} = 0.01

mm.
Diameter

= MSR + LC \times CSR = 1 + 0.01 \times 42 = 1.42

mm.
Given diameter

= \frac{x}{50}

mm, so

x = 1.42 \times 50 = 71.

JEE Main · 2024 · 06 Apr 2024 · Shift 1 · Single correct option

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