Fig. 10.1 shows a relay connected to a cell and a switch. [Figure 10.1]

1. (a)(i)On Fig. 10.1, mark 1. the S-pole of the iron core 2. the N-pole and the S-pole of the iron armature.[2]
2. (a)(ii)The cell is reversed. State what happens to the poles and to the armature.[2]
3. (a)(iii)Explain why the core is made of iron and not steel.[2]
4. (b)(i)Fig. 10.2 shows the relay connected in a circuit to a 12V battery. The bell is not ringing. [Figure 10.2] State the name of component X.[1]
5. (b)(ii)Explain why the bell rings when the temperature of X rises.[2]
6. (b)(iii) 1.When the resistance of X is 2000 Ω, the current in the coil is 1.5mA. This causes the contacts in the relay to close. The resistance of the bell is 200Ω. Calculate the potential difference (p.d.) across X, p.d. =[2]
7. (b)(iii) 2.the p.d. across the coil, p.d. =[1]
8. (b)(iii) 3.the current in the battery. current =[2]
9. (b)(iv)Component X is removed from the circuit and replaced by a different component Y. The bell now rings when bright light shines on Y. State the name of component Y.[1]

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