Physics – 4.3.2 Series and parallel circuits | e-Consult
4.3.2 Series and parallel circuits (1 questions)
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Materials:
- Battery (e.g., 9V)
- Battery holder
- Connecting wires
- A switch
- A variable resistor (rheostat)
- An ammeter
- A circuit diagram (see below)
Procedure:
- Construct a circuit according to the diagram below. The rheostat will allow you to vary the resistance in the circuit.
- Connect the ammeter in series with one of the wires in the circuit.
- Set the rheostat to a low resistance.
- Close the switch and record the ammeter reading (current, I).
- Increase the resistance of the rheostat in steps, recording the ammeter reading for each value. Take at least 5 readings.
Circuit Diagram:
| + Battery |
| | |
| --- Rheostat --- Ammeter --- Wire --- Junction --- Wire --- Battery - |
Results Recording: Create a table to record your results:
| Resistance (Ω) | Current (A) |
| 10 | 0.5 |
| 20 | 0.4 |
| 30 | 0.3 |
| 40 | 0.25 |
Demonstration: The results will demonstrate that as the resistance of the circuit increases, the current through the ammeter decreases. However, the current remains constant at the junction. This is because the current entering the junction is the same as the current leaving the junction, as required by the junction rule. The rheostat allows us to control the resistance, but the total current flowing through the junction remains the same.