CSEC Physics · January 2015 · Paper 2 · Question 5(b)(iv)

The brightness of the incandescent bulb in Figure 4 may be increased by varying the rheostat between 0 Ω and 100 Ω. When lit, the bulb operates at 0.30 A and 3.0 V.

The assumption made in (b)(ii) is incorrect. With the aid of an I-V graph, indicate how the bulb's resistance actually varies with current.

This question uses a figure or table from the paper — you'll see it when you practise.