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1.Units, Dimensions and Measurement
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Student $A$ and Student $B$ used two screw gauges of equal pitch and $100$ equal circular divisions to measure the radius of a given wire. The actual value of the radius of the wire is $0.322\, {cm}$. The absolute value of the difference between the final circular scale readings observed by the students $A$ and $B$ is .... .
[Figure shows position of reference $'O'$ when jaws of screw gauge are closed]
Given pitch $=0.1 \,{cm}$.
A
$13$
B
$26$
C
$39$
D
$130$
(JEE MAIN-2021)
Solution
For $A$
Reading $=$ MSR $+$ CSR $+$ Error
$0.322=0.300+C S R+5 \times L C$
$0.322=0.300+C S R+0.005$
$C S R=0.017$
For $B$
Reading $=$ MSR $+$ CSR $+$ Error
$0.322=0.200+C S R+0.092$
$C S R=0.030$
Difference $=0.030-0.017=0.013 cm$
Division on circular scale $=\frac{0.013}{0.001}=13$
Standard 11
Physics
