Practise predicting how an LDR’s resistance changes with light intensity and applying the relationship to circuit or sensor behaviour and graph direction.
The circuit in (a) is now modified by adding a uniform resistance wire XY and a galvanometer, as shown in Fig. 7.2.
Fig. 7.2 (not to scale)
The length of the wire XY is 1.2 m . The movable connection Z is positioned on the wire XY so that the galvanometer reading is zero.
The environmental conditions change causing a decrease in the resistance of the LDR. The temperature of the LDR remains constant.
State whether there is a decrease, increase or no change to:
- the intensity of the light illuminating the LDR
- the total power produced by the battery
- the length XZ so that the galvanometer reads zero.