Question

The diagram below shows a circuit containing a lamp L, a voltmeter and an ammeter,. The voltmeter reading 3 V and the ammeter reading is 0.5 A. 

  

 What is the resistance of the lamp?
 What is the power of the lamp?

Answer 1

 Given:
        Potential difference = reading of the voltmeter, V = 3 V
        Current in the circuit = reading of the ammeter, I= 0.5 A
        (i)  Resistance of the lamp, `R=V/I=(3V)/0.54=6 ohm`
        (ii) Power, P = VI = 3 V x 0.5 A = 1.5 W