A student designs a temperature-sensing bridge circuit to detect temperature changes in a greenhouse. The circuit diagram is shown below.
The DC supply has an electromotive force (e.m.f.) of 12 V and negligible internal resistance.
At a temperature of 15 ∘C15\ ^\circ\text{C}15 ∘C, the resistance of the negative temperature coefficient (NTC) thermistor T T\,T is 3.6 kΩ3.6\text{ k}\Omega3.6 kΩ.
What is the reading on the voltmeter at 15 ∘C15\ ^\circ\text{C}15 ∘C?
0.5 V0.5\text{ V}0.5 V
1.5 V1.5\text{ V}1.5 V
3.5 V3.5\text{ V}3.5 V
11.5 V11.5\text{ V}11.5 V