A voltmeter with internal resistance of can be used to measure upto 20 V. In order to increase its measuring range to 30 V

Question

A voltmeter with internal resistance of $x Ω$ can be used to measure upto 20 V. In order to increase its measuring range to 30 V, the required modification is to ________. [2026]

Smart Achievers · Accepted Answer

(1)

$20 = I_{g} x$

$30 = I_{g} (x + x')$

$3 x = 2 x + 2 x'$

$x' = \frac{x}{2}$

Solution

Q.
A voltmeter with internal resistance of $x Ω$ can be used to measure upto 20 V. In order to increase its measuring range to 30 V, the required modification is to ________. [2026]

1 connect resistor of $\frac{x}{2} Ω$ , in series with voltmeter.

2 connect resistor of $\frac{x}{2} Ω$ , in parallel to voltmeter.

3 connect resistor of $x Ω$ , in series with voltmeter.

4 connect resistor of $2 x Ω$ , in parallel to voltmeter.

Ans.
(1)

$20 = I_{g} x$

$30 = I_{g} (x + x')$

$3 x = 2 x + 2 x'$

$x' = \frac{x}{2}$

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Solution

Q. A voltmeter with internal resistance of x Ω can be used to measure upto 20 V. In order to increase its measuring range to 30 V, the required modification is to ________. [2026]

1 connect resistor of x2 Ω, in series with voltmeter.

2 connect resistor of x2 Ω, in parallel to voltmeter.

3 connect resistor of x Ω, in series with voltmeter.

4 connect resistor of 2x Ω, in parallel to voltmeter.

Ans. (1) 20=Igx 30=Ig(x+x') 3x=2x+2x' x'=x2