Two voltmeters are available in the laboratory

PHYSICS · Multi-part · A Level · Physics · Electricity · Electricity

Problem

Two voltmeters are available in the laboratory. • Voltmeter V1V_{1}: range 0–10 V0\text{–}10\,\text{V}, internal resistance 10 kΩ10\,\text{k}\Omega • Voltmeter V2V_{2}: range 0–20 V0\text{–}20\,\text{V}, internal resistance 20 kΩ20\,\text{k}\Omega A circuit consists of a 12 V12\,\text{V} battery connected to a 10 Ω10\,\Omega resistor. When no measuring instrument is attached, the current in the circuit is 0.6 A0.6\,\text{A}. (a) Calculate the potential difference across the 10 Ω10\,\Omega resistor under these conditions. (b) Which voltmeter, V1V_{1} or V2V_{2}, should be chosen to measure this potential difference so that the circuit is disturbed as little as possible? Give two reasons based on the data provided. (c) The chosen voltmeter is now connected correctly across the resistor. Calculate the new potential difference across the resistor, taking into account the loading effect of the voltmeter. (Treat the voltmeter resistance as being in parallel with the resistor.) (d) Find the percentage error between the value obtained in part (a) and the value obtained in part (c).

Related theory

Browse the problem library