A student investigates the relationship between the length lll of a resistance wire and its resistance RRR. The student measures a constant current in the circuit:
I=0.45 A I = 0.45\text{ A} I=0.45 AThe table below shows the student's measurements of length lll and potential difference VVV.
| l/cml / \text{cm}l/cm | V/VV / \text{V}V/V | R/ΩR / \OmegaR/Ω |
|---|---|---|
| 20.0 | 0.62 | (i) |
| 40.0 | 1.26 | (ii) |
| 60.0 | 1.85 | (iii) |
| 80.0 | 2.50 | (iv) |
| 100.0 | 3.12 | (v) |
Calculate the resistance RRR of each length of wire using the equation R=VIR = \frac{V}{I}R=IV. Write down the calculated values for (i) to (v) to two decimal places.
Select the statement that best describes the relationship between RRR and lll from the results:
Justify your choice by reference to your calculated values.
Use the values in the table to estimate the potential difference VeV_{\mathrm{e}}Ve across 50.0 cm50.0\text{ cm}50.0 cm of the resistance wire.
Calculate the resistance of 50.0 cm50.0\text{ cm}50.0 cm of the resistance wire using the equation:
R=VeI R = \frac{V_{\mathrm{e}}}{I} R=IVeState your answer to a suitable number of significant figures (2 or 3) and include the unit.
452 exam-style questions on CIE IGCSE Physics 4.2 Electrical quantities, covering 4.2.1a Positive and negative charge, 4.2.1b Charging by friction and detecting charge, 4.2.1c Electrical conductors and insulators, 4.2.1d Electric fields and electric field patterns, 4.2.2a Electric current, charge and measuring current, 4.2.2b Conduction in metals and the direction of current, 4.2.2c Direct current and alternating current, 4.2.3a Electromotive force, 4.2.3b Potential difference and voltmeters, 4.2.4a Resistance, 4.2.4b Resistance of a metallic wire, 4.2.4c Current–voltage graphs, and 4.2.5 Electrical energy and electrical power. Each one has a worked solution and a mark scheme showing where the marks go.