S L Arora Solutions for Chapter: Magnetic Effect of Current, Exercise 1: Problems For Practice

A shunt of $6 \mathrm{\Omega }$ is connected across a galvanometer of resistance $294 \mathrm{\Omega }$. Find the fraction of the total current passing through the galvanometer.

It is required to pass only one‐tenth of the main current through a galvanometer having a resistance of $27 \mathrm{\Omega }$. Calculate the length of the wire of specific resistance $48\times {10}^{-6}\mathrm{ }\mathrm{\Omega } \mathrm{cm}$ and area of cross‐section $0.2 {\mathrm{nm}}^2$ required to make a shunt for this purpose.

A galvanometer gives a full-scale deflection with a current of $1 A$. It is converted into ammeter of range $10 A$. Find the ratio of the resistance of the ammeter to the resistance of the shunt used.

A galvanometer has a resistance of $8 \mathrm{\Omega }$. It gives a full-scale deflection for a current of $10 mA$. It is to be converted into an ammeter of range $5 A$. The only shunt resistance available is of $0.02 \mathrm{\Omega }$, which is not suitable for this conversion. Find the value of resistance $R$ that must be connected in series with the galvanometer (Figure) to get ammeter of desired range.

The circuit shown in Figure is used to measure the resistance $R$. The ammeter reads $0.13 A$ and the voltmeter reads $117 V$. The resistance of the ammeter is $0.015 \mathrm{\Omega }$ and that of the voltmeter is $9000 \mathrm{\Omega }$. Find the value of $R$.

The scale of a galvanometer is divided into $150$ equal divisions. The galvanometer has the current sensitivity of $10$ divisions per $\mathrm{mA}$ and the voltage sensitivity of $2$ divisions per $\mathrm{mV}$. How the galvano‐ meter can be designed to read (i) $6 \mathrm{A} {\mathrm{division}}^{-1}$ and (ii) $1 \mathrm{V} {\mathrm{division}}^{-1}$?

Two resistance coils of $100 \mathrm{\Omega }$ and $200 \mathrm{\Omega }$ respectively are connected in series across $100 \mathrm{V}$. A moving coil voltmeter of $200 \mathrm{\Omega }$ is connected in turn across each coil. What will it read in each case?

A battery of emf $12 \mathrm{V}$ and internal resistance $1.2 \mathrm{\Omega }$ supplies a current through a coil of resistance $48 \mathrm{\Omega }$. A voltmeter of resistance $72 \mathrm{\Omega }$ is used to measure the potential difference across the coil. What would be the reading on the voltmeter?