5 A student sets up a circuit using a battery made of four cells, a resistor R, two identical lamps P and Q, and a switch. (c) The resistnace of resistor R is 18. The combined resistance of P, Q and R in the circuit is 12. Calculate the resistance of lamp Q. [Ans : 7.52] battery lamp Q switch resistor R lamp P Resistance of lamp Q= (d) Explain why, in this circuit, (i) the current in lamp Q is larger than the current in lamp P, (a) Draw a circuit diagram of this circuit using electrical symbols for the components. (ii) lamp Q has a different resistance from lamp P, even though they are identical lamps. (b) The switch is closed. The current in lamp P is 0.25 A and there is a potential difference (p.d.) of 1.5 V across its terminals. Calculate the resistance of lamp P. [Ans: 6.02] Resistance of lamp P =