A student investigates the resistance of a resistance wire using a practical setup. Keeping the current in the circuit constant at I=0.40 AI = 0.40\text{ A}I=0.40 A, the student records the potential difference VVV across different lengths lll of the wire.
The student's readings are shown in the table below:
| l / cml\text{ / cm}l / cm | V / VV\text{ / V}V / V | Vl / (Vcm)\frac{V}{l}\text{ / }\left(\frac{\text{V}}{\text{cm}}\right)lV / (cmV) |
|---|---|---|
| 20.020.020.0 | 0.520.520.52 | |
| 40.040.040.0 | 1.041.041.04 | |
| 60.060.060.0 | 1.561.561.56 | |
| 80.080.080.0 | 2.082.082.08 | |
| 100.0100.0100.0 | 2.602.602.60 |
Complete the table by calculating and recording the values of Vl\frac{V}{l}lV to a consistent number of significant figures (2 or 3).
State your conclusion from these values of Vl\frac{V}{l}lV.
Justify your conclusion by referring to your calculated results.
Calculate the resistance RRR of the 100.0 cm100.0\text{ cm}100.0 cm length of the wire using the equation:
R=VI R = \frac{V}{I} R=IVwhere VVV is the potential difference across 100.0 cm100.0\text{ cm}100.0 cm of the wire. Give your answer to a suitable number of significant figures and include the correct unit.
Suggest one way to minimise the temperature rise of the resistance wire during this experiment.
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.