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

Two resistances are connected in two gaps of a metre bridge. The balance point is $20 \mathrm{cm}$ from the zero end. A resistance of $15 \mathrm{\Omega }$ is connected in series with the smaller of the two. The null point shifts to $40 \mathrm{cm}$. The value of the smaller resistance in $\mathrm{\Omega }$ is:

In a practical Wheatstone bridge circuit as shown, when one more resistance of $100 \mathrm{\Omega }$ is connected in parallel with an unknown resistance $x$, then ratio $l_1/l_2$ become $2. l_1$ is balance length and $AB$ is a uniform wire. Then value of $x$ must be:

A resistance $R$ is to be measured using a meter bridge, the student chooses the standard resistance $S$ to be $100 \mathrm{\Omega }$. He finds the null point at $I_1=2.9 \mathrm{cm}$. He is told to attempt to improve the accuracy. Which of the following is a useful way?

$R_1,R_2$ and $R_3$ are different values of $R$ and $A, B$ and $C$ are the null points obtained corresponding to $R_1,R_2$ and $R_3$ respectively. For which of the following the value of $X$ will be the most accurate:

In the shown arrangement of the experiment of the meter bridge, if $AC$ corresponding to null deflection of the galvanometer is $x$, what would be its value if the radius of the wire $AB$ is doubled?

In the circuit shown $P\ne R$, the reading of the galvanometer is same with switch $S$ open or closed. Then

The measurement of an unknown resistance $R$ is to be carried out using the Wheatstone bridge as given in the figure. Two students perform an experiment in two ways. The first students take $R_2=10 \mathrm{\Omega }$ and $R_1=5$$\mathrm{\Omega }$. The other student takes $R_2=1000 \mathrm{\Omega }$ and $R_1=500 \mathrm{\Omega }$. In the standard arm, both take $R_3=5 \mathrm{\Omega }$. Both find $R\mathit{=}\frac{{\mathit{R}}_{\mathit{2}}}{{\mathit{R}}_{\mathit{1}}}\mathit{,}\mathit{ }{R}_{\mathit{3}}=100 \mathrm{\Omega }$ within errors.

In a meter bridge, the point $\mathrm{D}$ is a neutral point (see figure).