The LDR and fixed resistor have resistances of $1800\,\Omega$ and $1200\,\Omega$ respectively. Calculate the potential difference across the LDR.
The circuit in part (a) is then changed by inserting a uniform resistance wire $XY$ and a galvanometer. The wire $XY$ has length $1.2\,\text{m}$. The sliding contact $Z$ is placed on wire $XY$ so that the galvanometer shows zero.
Calculate the length XZ along the resistance wire.
The environmental conditions change so that the resistance of the LDR decreases. The temperature of the LDR remains constant. State whether there is a decrease, increase or no change to: • the intensity of the light falling on the LDR • the total power produced by the battery • the length XZ so that the galvanometer reads zero.