JEE MAIN - Physics (2022 - 27th July Morning Shift - No. 1)
A torque meter is calibrated to reference standards of mass, length and time each with $$5 \%$$ accuracy. After calibration, the measured torque with this torque meter will have net accuracy of :
15%
25%
75%
5%
Explanation
We know that, torque applied on a rotating body,
$$
\begin{aligned}
\tau &=\text { Force } \times \text { Perpendicular distance } \\\\
\Rightarrow \quad[\tau] &=\left[\mathrm{MLT}^{-2}\right][\mathrm{L}] \Rightarrow[\tau]=\left[\mathrm{ML}^2 \mathrm{~T}^{-2}\right]
\end{aligned}
$$
$$ \Rightarrow {{\Delta \tau } \over \tau } = {{\Delta M} \over M} + 2{{\Delta L} \over L} + 2{{\Delta T} \over T}$$
$$ = 5 \times 5\% = 25\% $$
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