Series and Parallel Basics

IGCSE Edexcel Physics
2.7-2.8, 2.17-2.19 Circuits
Key Concepts: Series circuits share current; parallel circuits share voltage. Current is conserved at junctions.

Section A: Concepts

1. State one advantage of parallel circuits in the home. [2]
2. Describe how current and voltage behave in a series circuit. [3]
3. Describe how current and voltage behave in a parallel circuit. [3]

Section B: Simple Calculations

4. Two resistors of $3\,\Omega$ and $5\,\Omega$ are in series on a 12 V supply. Calculate the current. [3]
5. Calculate the voltage across each resistor in Question 4. [2]
6. Two $6\,\Omega$ resistors are connected in parallel to a 12 V supply. Calculate the total current. [3]
Total marks: 16

Mark Scheme

1. Components work independently; one failure does not break circuit [2]
2. Current same everywhere; voltage shared [3]
3. Voltage same across branches; current splits and recombines at junctions [3]
4. $R_{total} = 8\,\Omega$, $I = 12/8 = 1.5\,A$ [3]
5. $V_{3\Omega} = 1.5 \times 3 = 4.5\,V$, $V_{5\Omega} = 7.5\,V$ [2]
6. $R_{total} = 3\,\Omega$; $I = V/R = 12/3 = 4\,A$ [3]