Scale of galvanometer divided into 100 equal divisions has a current sensitivity 10 div./mA and voltage…

Scale of galvanometer divided into 100 equal divisions has a current sensitivity 10 div./mA and voltage sensitivity 4 div./mV. The resistance of galvanometer is
  1. $5 \Omega$
  2. $2.50$
  3. $10 \Omega$
  4. $7.5 \Omega$

Solution

$\frac{\mathrm{d} \theta}{\mathrm{dI}}=10 \mathrm{div} / \mathrm{m} \mathrm{A}, \frac{\mathrm{d} \theta}{\mathrm{dV}}=4 \operatorname{div} / \mathrm{mV}$ $\frac{\frac{\mathrm{d} \theta}{\mathrm{dI}}}{\frac{\mathrm{d} \theta}{\mathrm{dV}}}=\frac{\mathrm{dV}}{\mathrm{dI}}=\frac{10 \mathrm{mV}}{4 \mathrm{~mA}}=2.5 \Omega$

Asked in: MHT CET 2020 (14 Oct Shift 2)

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