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Home Questions WHMNS28TKB

Target Exam

CUET

Subject

Physics

Chapter

Current Electricity

Question:

Options:

a

b

c

d

Correct Answer:

b

Explanation:

When resistor $20 Ω$ is not connected,
From Ohms law $V = I R,$ we get $V = 25 R_{G} . . . (1)$ where $R_{G} =$ resistance of galvanometer.
When resistor $20 Ω$ is connected,
$V = 5 (20 + R_{G}) . . . (2)$
Using Equation 1 and 2, $25 R_{G} = 5 (20 + R_{G})$
$\Rightarrow 5 R_{G} = 20 + R_{G}$
$\Rightarrow 4 R_{G} = 20$ $\Rightarrow R_{G} = 5 Ω$

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