Question

The figure shows a circuit

When the circuit is switched on, the ammeter reads 0.5 A. 

(i) Calculate the value of the unknown resistor R.

(ii) Calculate the charge passing through the 3Ω resistor in 120 s. 

(iii) Calculate the power dissipated in the 3Ω resistor.

Answer 1

(i) let

(ii) Let q = it 

= 0.5 × 120 

∴ Charge q = 60 coulomb 

(iii) P = V.I. 

= I2R 

= (0.5)2 × 3 = 0.25 × 3 

∴ P = 0.75 watt.