JEE Mains · Physics · STD 12 - 4. Moving charges and magnetism
A voltmeter with internal resistance of \(x\ \Omega\) can be used to measure upto \(20\) V. In order to increase its measuring range to \(30\) V, the required modification is to _____.
- A connect resistor of \(\dfrac{x}{2}\ \Omega\), in series with voltmeter.
- B connect resistor of \(\dfrac{x}{2}\ \Omega\), in parallel to voltmeter.
- C connect a resistor of \(x\ \Omega\) in series with voltmeter.
- D connect resistor of \(2x\ \Omega\) in parallel to voltmeter.
Answer & Solution
Correct Answer
(A) connect resistor of \(\dfrac{x}{2}\ \Omega\), in series with voltmeter.
Step-by-step Solution
Detailed explanation
Let the maximum current for full-scale deflection of the voltmeter be \(I_g\). \(I_g = \dfrac{V_1}{R_v} = \dfrac{20}{x}\) To increase the measuring range to \(V_2 = 30\) V, a resistance \(R\) must be connected in series with the voltmeter. \(V_2 = I_g(R_v + R)\)…
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