A student is investigating how the resistance of a filament lamp changes with potential difference. They record the current III through the lamp for several potential difference VVV values, obtaining the following data:
| VVV (V) | III (A) |
|---|---|
| 1.5 | 0.24 |
| 3.0 | 0.40 |
| 4.5 | 0.50 |
| 6.0 | 0.58 |
| 7.5 | 0.64 |
Calculate the resistance RRR (in Ω\OmegaΩ) of the lamp for each potential difference value using the formula R=VIR = \frac{V}{I}R=IV. Record all values to 2 significant figures.
State the trend in the resistance of the lamp as the potential difference increases, and briefly explain this trend in terms of the behavior of the filament.
In a modified version of this experiment, the potential divider arrangement is replaced. State the standard circuit symbol for a variable resistor (rheostat) and state whether it should be connected in series or parallel with the lamp to change the current through it.
132 exam-style questions on CIE IGCSE Physics 4.2.4a Resistance. Each one has a worked solution and a mark scheme showing where the marks go.