State Kirchhoff’s second law for a closed loop.
A battery with electromotive force (e.m.f.) $9.0\,\text{V}$ and negligible internal resistance is joined in series with a variable resistor $X$ and a thermistor $Y$, as shown in Fig. 5.1. Fig. 5.2 gives the connection between temperature and resistance for the thermistor.
The circuit current is $1.1 \times 10^{-2}\,\text{A}$, and the potential difference across $Y$ is $4.0\,\text{V}$. Calculate the resistance of $X$.
The temperature of $Y$ is raised to $190^\circ\text{C}$. The resistance of $X$ stays unchanged. Determine the revised potential difference across $Y$.
The resistance of $X$ is increased. The temperature of $Y$ stays at $190^\circ\text{C}$. Referring to the circuit current, state and explain the effect of this change, if any, on the potential difference across $Y$.
The circuit current is $1.1 \times 10^{-2}\,\text{A}$, and the p.d. across Y is $4.0\,\text{V}$. Calculate the resistance of X.
The temperature of Y is changed to $190^\circ\text{C}$. The resistance of X remains unchanged. Determine the new potential difference across Y.
The resistance of X is increased. The temperature of Y remains at $190^\circ\text{C}$. By referring to the current in the circuit, state and explain the effect of this change, if any, on the potential difference across Y.