Chapter: Current Electricity· Physics

A galvanometer has a resistance of 30 Ω and its full scale deflection current is 20 microampere (µA). What resistance should be added to it to have a range 0-10 volt?

Q.7 A galvanometer has a resistance of 30 Ω and its full scale deflection current is 20 microampere (µA). What resistance should be added to it to have a range 0-10 volt?

Doubtly Asked 29 Oct 2026 Board exam · March 2024 hsc 12th Save WhatsApp Report

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Answer: A resistance of 499970 Ω (about \(5\times10^5\) Ω) must be connected in series.

Given: \(G = 30\) Ω, \(I_g = 20\times10^{-6}\) A, \(V = 10\) V.

To make a voltmeter, a high resistance \(R\) is connected in series: \(V = I_g(G + R)\).

\(R = \dfrac{V}{I_g} - G = \dfrac{10}{20\times10^{-6}} - 30 = 5\times10^{5} - 30 = 499970\) Ω.

Doubtly AI · 29 Oct 2026 AI-generated · not yet verified Report

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A galvanometer has a resistance of 30 Ω and its full scale deflection current is 20 microampere (µA). What resistance should be added to it to have a range 0-10 volt?

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