AQA GCSE FOUNDATION Physics: Investigating the Characteristics of DC Circuits

Investigating DC Circuits: Exploring Resistance in Series and Parallel

This tutorial explores the characteristics of Direct Current (DC) circuits, focusing on resistance in series and parallel configurations. You'll learn how to build circuits, measure voltage and current, calculate resistance, and analyze how the total resistance changes in each configuration.

Materials:

• DC power supply
• Ammeter
• Voltmeter
• Resistors (at least 3 with different resistances)
• Connecting wires
• Switch

Understanding Resistance:

Resistance is a measure of how difficult it is for electric current to flow through a material. It is measured in ohms (?).

Ohm's Law:

Ohm's Law states that the current flowing through a conductor is directly proportional to the voltage applied across its ends and inversely proportional to its resistance. Mathematically:

V = IR

Where:

• V is voltage (measured in volts, V)
• I is current (measured in amperes, A)
• R is resistance (measured in ohms, ?)

Building a Series Circuit:

1. Connect the power supply, a switch, and the first resistor in series.
2. Connect the ammeter in series with the resistor, to measure the current flowing through it.
3. Connect the voltmeter in parallel with the resistor, to measure the voltage across it.

Building a Parallel Circuit:

1. Connect the power supply and a switch.
2. Connect each resistor to the power supply in separate branches, creating a parallel configuration.
3. Connect the ammeter in series with the power supply, to measure the total current flowing through the circuit.
4. Connect voltmeters in parallel with each resistor, to measure the voltage across each one.

Measurements and Calculations:

1. Series Circuit:
2. Close the switch and record the current and voltage readings.
3. Calculate the resistance of each resistor using Ohm's Law (R = V / I).
4. Calculate the total resistance of the circuit by adding the individual resistances.

5. Repeat the measurements and calculations with different combinations of resistors in series.

6. Parallel Circuit:

7. Close the switch and record the current and voltage readings for each resistor.
8. Calculate the resistance of each resistor using Ohm's Law.
9. Calculate the total resistance of the circuit using the following formula:

1/Rtotal = 1/R1 + 1/R2 + 1/R3...

• Repeat the measurements and calculations with different combinations of resistors in parallel.

Analysis:

• Compare the total resistance in series and parallel circuits.
• Observe how the total current changes with the addition of more resistors in series and parallel.
• Explain how the distribution of voltage and current differs in series and parallel circuits.

Conclusion:

• Summarize your findings on how resistance affects the behavior of DC circuits in series and parallel configurations.
• Discuss the importance of understanding these concepts in real-world applications.

Further Exploration:

• Investigate the effect of changing the resistance of individual components in series and parallel circuits.
• Explore the concepts of power dissipation and energy transfer in DC circuits.
• Build more complex circuits with combinations of series and parallel connections.

Safety Precautions:

• Always ensure the circuit is disconnected from the power supply before making any changes.
• Use caution when handling electrical components, especially those connected to a power source.
• Never touch any wires or components while the circuit is live.