For designing a voltmeter of range 50 V and an ammeter of range 10 mA using a galvanometer which has a coil of resistance 54 showing a full-scale deflection for 1 mA as shown in figure. [2023]

Question

For designing a voltmeter of range 50 V and an ammeter of range 10 mA using a galvanometer which has a coil of resistance 54 $Ω$ showing a full-scale deflection for 1 mA as shown in figure. [2023]

(A) for voltmeter $R \approx 50 k Ω$
(B) for ammeter $r \approx 0.2 Ω$
(C) for ammeter $r \approx 6 Ω$
(D) for voltmeter $R \approx 5 k Ω$
(E) for voltmeter $R \approx 500 Ω$

Choose the correct answer from the options given below:

Smart Achievers · Accepted Answer

(3)

$For voltmeter$

$R = \frac{V}{I_{g}} - G = \frac{50}{10^{- 3}} - 54 \approx 50 k Ω (A)$

$For ammeter$

$S = \frac{I_{g} G}{I - I_{g}} = \frac{10^{- 3} \times 54}{(10 - 1) \times 10^{- 3}} = 6 Ω (C)$

Solution

1 (C) and (E)

2 (C) and (D)

3 (A) and (C)

4 (A) and (B)

Ans.
(3)

$For voltmeter$

$R = \frac{V}{I_{g}} - G = \frac{50}{10^{- 3}} - 54 \approx 50 k Ω (A)$

$For ammeter$

$S = \frac{I_{g} G}{I - I_{g}} = \frac{10^{- 3} \times 54}{(10 - 1) \times 10^{- 3}} = 6 Ω (C)$

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