Question

You are given three resistors of 10 Ω, 10 Ω and 20 Ω, a battery of emf 2.5 V, a key, an ammeter and a voltmeter. Draw a circuit diagram showing the correct connections of all given components such that the voltmeter connected across the ends of 20 ​Ω resistor gives a reading of 2.0 V.

Answer 1

The ammeter and key are connected in series with the battery and the resistors. We have connected two 10 Ω resistors in parallel and its combination is in series with another 20 Ω resistor. This is because the effective resistance of two 10 Ω resistors, connected in parallel will be 5 Ω and will consume only 0.5 volts from the battery. The remaining 2 volts will be consumed by the 20 Ω resistors. Thus, the voltmeter connected in parallel with it will show a reading of 2 volts.