Diagram Or Graph Drill — Electricity and magnetism
Sketch one complete cycle of the output voltage from a simple a.c. generator. Use a horizontal time axis and a vertical voltage axis. Label one peak positive voltage, one peak negative voltage, and the period.
Diagram Or Graph Drill — Electricity and magnetism
Draw a voltage-time graph for an a.c. generator with peak voltage 6.0 V and period 0.20 s. Show two complete cycles from t = 0 to t = 0.40 s.
Diagram Or Graph Drill — Electricity and magnetism
Two a.c. generator outputs are compared. Generator X has peak voltage 4 V and period 0.50 s. Generator Y rotates faster and has peak voltage 4 V and period 0.25 s. On the same axes, sketch both voltage-time graphs from 0 to 0.50 s and label X and Y.
Experiment Planning Task — Electricity and magnetism
Plan an experiment to investigate how the length of a resistance wire affects the current in a circuit. You may use a low-voltage power supply, switch, ammeter, voltmeter, metre ruler, crocodile clips and resistance wire. Include the variables, method, table and graph.
Experiment Planning Task — Electricity and magnetism
Plan an experiment to investigate how the number of turns on a coil affects the strength of an electromagnet. You may use insulated copper wire, an iron nail, a low-voltage d.c. supply, switch, paper clips, ammeter and connecting leads. Include safety and reliability details.
Data Interpretation Drill — Electricity and magnetism
An electrical component has the following data. Potential difference / V: 0, 1, 2, 3, 4. Current / A: 0, 0.20, 0.40, 0.60, 0.80. Describe the relationship between current and potential difference and calculate the resistance.
Data Interpretation Drill — Electricity and magnetism
A lamp is tested. Potential difference / V: 0, 1, 2, 3, 4, 5. Current / A: 0, 0.18, 0.31, 0.41, 0.49, 0.55. Explain what happens to the resistance as potential difference increases.
Data Interpretation Drill — Electricity and magnetism
Two components are tested. At 2.0 V, component A has current 0.40 A and component B has current 0.10 A. At 6.0 V, A has current 1.20 A and B has current 0.20 A. Identify which component is ohmic and justify your answer.
Worked Example — Electricity and magnetism
Worked example: A resistor is tested. Potential difference / V: 1.5, 3.0, 4.5, 6.0. Current / A: 0.30, 0.60, 0.90, 1.20. Decide whether the resistor is ohmic and find its resistance.
Solution
Step 1: For an ohmic resistor, V is directly proportional to I and resistance is constant. Step 2: Calculate R = V/I using one pair: R = 3.0/0.60 = 5.0 Ω. Step 3: Check another pair: R = 6.0/1.20 = 5.0 Ω. Step 4: Since resistance is constant, the resistor is ohmic.