Question 172: Current Electricity

Question

For designing a voltmeter of range $50 \mathrm{~V}$ and an ammeter of range $10 \mathrm{~mA}$ using a galvanometer which has a coil of resistance $54 \Omega$ showing a full scale deflection for $1 \mathrm{~mA}$ as in figure.

(A) for voltmeter $R \approx 50 \mathrm{k} \Omega$
(B) for ammeter $\mathrm{r} \approx 0.2 \Omega$
(C) for ammeter $\mathrm{r}=6 \Omega$
(D) for voltmeter $R \approx 5 \mathrm{k} \Omega$
(E) for voltmeter $R \approx 500 \Omega$
Choose the correct answer from the options given below:

Accepted Answer

For voltmeter
$$
\begin{aligned}
& \mathrm{R}=\frac{\mathrm{V}}{\mathrm{I}_{\mathrm{g}}}-\mathrm{G} \\
& =\frac{50}{10^{-3}}-54 \approx 50 \mathrm{k} \Omega~(\mathrm{A})
\end{aligned}
$$
For ammeter
$$
\mathrm{S}=\frac{\mathrm{I}_{\mathrm{g}} \mathrm{G}}{\mathrm{I}-\mathrm{I}_{\mathrm{g}}}=\frac{10^{-3} 	imes 54}{(10-1) 	imes 10^{-3}}=6 \Omega~(\mathrm{C})
$$

Answer

$(\mathrm{A})$ and $(\mathrm{C})$

Answer

(A) and (B)

Answer

(C) and (E)

Answer

(C) and (D)

Current Electricity

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