CAPE Physics Unit 2 · 2013 · Paper 2 · Question 5(b)(iii)

Figure 5 shows a circuit implementation with an open-loop op-amp comparator, an LDR, logic circuit in dashed box P, switching amplifier, and relay.

Describe how a relay functions, stating why this device is necessary in the circuit.

This question uses a figure or table from the paper — you'll see it when you practise.