Show that the equivalent resistance $R$ for the network is $R = R_1 + R_2 + R_3$.
A battery with electromotive force (e.m.f.) $8.0\,\text{V}$ and negligible internal resistance is connected to a thermistor, a switch X and two fixed resistors, as shown in Fig. 6.2. The resistance of resistor $R_1$ is $6.0\,\text{k}\Omega$ and that of resistor $R_2$ is $4.0\,\text{k}\Omega$.
The switch X is open. Calculate the potential difference across $R_1$.
Switch X is now closed. The thermistor has resistance $12.0\,\text{k}\Omega$. Calculate the current in the battery.
In the circuit in (b), switch X stays closed. The thermistor’s temperature falls. Referring to the current in the battery, state and explain the effect, if any, of the temperature decrease on the power produced by the battery.