If only $2 \%$ of the total current passes through an ammeter having coil of resistance ${ }^{\prime}…

If only $2 \%$ of the total current passes through an ammeter having coil of resistance ${ }^{\prime} \mathrm{R}^{\prime}$ then the resistance of the shunt of an ammeter is
  1. $49 \mathrm{R}$
  2. $\frac{\mathrm{R}}{50}$
  3. $\frac{\mathrm{R}}{49}$
  4. $50 \mathrm{R}$

Solution

$\frac{\mathrm{I}_{\mathrm{g}}}{\mathrm{I}}=\frac{2}{100}=\frac{1}{50}$ $\frac{\mathrm{I}_{\mathrm{g}}}{\mathrm{I}}=\frac{\mathrm{S}}{\mathrm{S}+\mathrm{R}} \quad \therefore \quad \frac{1}{50}=\frac{\mathrm{S}}{\mathrm{S}+\mathrm{R}}$ $\mathrm{S}+\mathrm{R}=50 \mathrm{~S}$ $\mathrm{R}=50 \mathrm{~S}, \mathrm{R}=49 \mathrm{~S}$ or $\mathrm{S}=\frac{\mathrm{R}}{49}$

Asked in: MHT CET 2020 (13 Oct Shift 2)

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