GCSE Combined Science (AQA)

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Resistance in Parallel

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Electricity Series and parallel circuits

Resistance in Parallel

7:30 Parallel Circuits
Spec 4.2.2
Previous Current & Potential Difference in Parallel Next Comparing Series & Parallel Circuits
  • Increasing the number of resistors in parallel decreases the total resistance of a circuit.
  • Comparing two circuits: one with a single series resistor and another with two parallel resistors, both with resistance R.
  • The parallel circuit surprisingly has a lower total resistance compared to the series circuit.
  • Adding resistors in parallel decreases total resistance and increases total current in the circuit.
  • Demonstrated using circuits with lamps instead of resistors, maintaining the same potential difference (V) and resistance (R) for each lamp.
  • The equation V = IR (Ohm's Law) is used to relate current, resistance, and potential difference in the circuit.
  • In parallel circuits, the total potential difference remains constant, but the lower total resistance results in a higher total current.
  • The current is split between parallel branches, and the branch with lower resistance receives a higher share of the current.
  • Example given with a lamp and a resistor in parallel branches, where the branch with higher resistance (6 ohms) has lower current compared to the branch with lower resistance (1 ohm).
  • If a branch has no components, almost all the current will travel down this branch due to almost zero resistance.
  • Closing a switch in a parallel branch with no components allows current to flow through it, reducing the current in other branches with higher resistance, potentially causing a lamp in another branch to stop glowing.

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