ElectricityAQA GCSE Physics (8463)

Series and Parallel Circuits

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next. (2026)

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Master the topic

Worked examples2 Key formulae1 Definitions2 Common mistakes2

Step-by-step worked examples

01.Series voltage sharing
Foundation
Question
A 9 V cell drives current through a 6 Ω and a 3 Ω resistor in series. Find the p.d. across each resistor.
Solution
1. 1
  Total R.
  $R = 6 + 3 = 9\,\text{Ω}$
2. 2
  Current.
  $I = V/R = 9/9 = 1\,\text{A}$
3. 3
  p.d. across each resistor.
  $V_6 = 1 \times 6 = 6\,\text{V};\quad V_3 = 1 \times 3 = 3\,\text{V}$
Answer
6 V across the 6 Ω; 3 V across the 3 Ω. Total = 9 V (= cell).
02.Parallel branch currents
Foundation
Question
Three bulbs are in parallel across a 12 V battery. The bulb currents are 0.5, 0.3 and 0.2 A. What is the cell's current?
Solution
1. 1
  Apply the parallel current rule.
  $I_{\text{total}} = 0.5 + 0.3 + 0.2 = 1.0\,\text{A}$
2. 2
  Voltage across each bulb is the same.
  $V_{\text{each}} = 12\,\text{V}$
Answer
Cell current = 1.0 A. Each bulb has 12 V across it.

Key formulae

Series resistance
$R_{\text{total}} = R_1 + R_2 + \ldots$
- $R_{\text{total}}$
  — Combined series resistance (Ω)
- $R_1, R_2$
  — Individual resistances (Ω)
When to use
Series circuits only.

Practice with flashcards

Card 1 of 20 known · 0 to review

Key definitions and keywords

Series circuitExaminer keyword: A circuit where components are connected in a single loop, with no branches.
Parallel circuitExaminer keyword: A circuit with two or more branches, each providing an independent current path between the same two points.

Common mistakes and misconceptions

Mistake
Adding resistances in parallel (e.g. 4 + 6 = 10 Ω).
Why it happens
Series rule misapplied.
How to avoid it
Parallel total is LESS than the smallest individual R. Don't add.
Mistake
Mixing up which quantity adds.
Why it happens
Two rule sets to remember.
How to avoid it
Series: I same, V/R add. Parallel: V same, I/(1/R) add.

ElectricityAQA GCSE Physics (8463)

Series and Parallel Circuits

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next. (2026)

Previous Next

Master the topic

Worked examples2 Key formulae1 Definitions2 Common mistakes2

Step-by-step worked examples

01.Series voltage sharing
Foundation
Question
A 9 V cell drives current through a 6 Ω and a 3 Ω resistor in series. Find the p.d. across each resistor.
Solution
1. 1
  Total R.
  $R = 6 + 3 = 9\,\text{Ω}$
2. 2
  Current.
  $I = V/R = 9/9 = 1\,\text{A}$
3. 3
  p.d. across each resistor.
  $V_6 = 1 \times 6 = 6\,\text{V};\quad V_3 = 1 \times 3 = 3\,\text{V}$
Answer
6 V across the 6 Ω; 3 V across the 3 Ω. Total = 9 V (= cell).
02.Parallel branch currents
Foundation
Question
Three bulbs are in parallel across a 12 V battery. The bulb currents are 0.5, 0.3 and 0.2 A. What is the cell's current?
Solution
1. 1
  Apply the parallel current rule.
  $I_{\text{total}} = 0.5 + 0.3 + 0.2 = 1.0\,\text{A}$
2. 2
  Voltage across each bulb is the same.
  $V_{\text{each}} = 12\,\text{V}$
Answer
Cell current = 1.0 A. Each bulb has 12 V across it.

Key formulae

Series resistance
$R_{\text{total}} = R_1 + R_2 + \ldots$
- $R_{\text{total}}$
  — Combined series resistance (Ω)
- $R_1, R_2$
  — Individual resistances (Ω)
When to use
Series circuits only.

Practice with flashcards

Card 1 of 20 known · 0 to review

Key definitions and keywords

Series circuitExaminer keyword: A circuit where components are connected in a single loop, with no branches.
Parallel circuitExaminer keyword: A circuit with two or more branches, each providing an independent current path between the same two points.

Common mistakes and misconceptions

Mistake
Adding resistances in parallel (e.g. 4 + 6 = 10 Ω).
Why it happens
Series rule misapplied.
How to avoid it
Parallel total is LESS than the smallest individual R. Don't add.
Mistake
Mixing up which quantity adds.
Why it happens
Two rule sets to remember.
How to avoid it
Series: I same, V/R add. Parallel: V same, I/(1/R) add.

Series and Parallel Circuits

Master the topic

Step-by-step worked examples

01.Series voltage sharing

02.Parallel branch currents

Key formulae

Practice with flashcards

Key definitions and keywords

Common mistakes and misconceptions

Series and Parallel Circuits

Master the topic

Step-by-step worked examples

01.Series voltage sharing

02.Parallel branch currents

Key formulae

Practice with flashcards

Key definitions and keywords

Common mistakes and misconceptions