B M Sharma Solutions for Chapter: Electrical Measuring Instruments, Exercise 4: Archives

Which of the following statement is false?

When a current of $5 \mathrm{mA}$ is passed through a galvanometer having a coil of resistance $15 \mathrm{\Omega }$, it shows full-scale deflection. The value of the resistance to be put in series with the galvanometer to convert it into voltmeter of range $0-10 \mathrm{V}$ is

On interchanging the resistances, the balance point of a meter bridge shifts to the left by $10 \mathrm{cm}$. The resistance of their series combinations is $1 \mathrm{k\Omega }$. How much was the resistance on the left slot before interchanging the resistances?

In a potentiometer experiment, it is found that no current passes through the galvanometer when the terminals of the cell are connected across $52 \mathrm{cm}$ of the potentiometer wire. If the cell is shunted by a resistance of $5 \mathrm{\Omega }$, a balance is found when the cell is connected across $40 \mathrm{cm}$ of the wire. Find the internal resistance of the cell.

To verify Ohm's law, a student is provided with a test resistor $R_{\mathrm{T}}$, a high resistance $R_1$, a small resistance $R_2$, two identical galvanometers $G_1$ and $G_2$ and a variable voltage source $V$. The correct circuit to carry out the experiment is

Consider two identical galvanometers and two identical resistors with resistance $R$. If the internal resistance of the galvanometers $R_C<R/2$, which of the following statement(s) about any one of the galvanometers is (are) true?

A galvanometer gives full scale deflection with $0.006 \mathrm{A}$ current. By connecting it to a $4990 \mathrm{\Omega }$ resistance, it can be converted into a voltmeter of range $0-30 \mathrm{V}$. If connected to a $\frac{2n}{249} \mathrm{\Omega }$ resistance, it becomes an ammeter of range $0-1.5 \mathrm{A}$. The value of $n$ is,

A moving coil galvanometer has $50$ turns and each turn has an area of $2\times {10}^{-4}{ \mathrm{m}}^2$. The magnetic field produced by the magnet inside the galvanometer is $0.02 \mathrm{T}$. The torsional constant of the suspension wire is ${10}^{-4} \mathrm{N} \mathrm{m} {\mathrm{rad}}^{-1}$. When a current flows through the galvanometer, a full-scale deflection occurs if the coil rotates by $0.2 \mathrm{rad}$. The resistance of the coil of the galvanometer is $50 \mathrm{\Omega }$. This galvanometer is to be converted into an ammeter capable of measuring current in the range $0-1.0 \mathrm{A}$. For this purpose, a shunt resistance is to be added in parallel to the galvanometer. The value of this shunt resistance, in ohms, is,