Grade 11 · Physics
Calculate current in a series circuit
In a series circuit there is one path for current, so the same current flows through each component. For Grade 11 circuit revision, add series resistances and use V = IR to find the current when resistance is constant. The supply potential difference is shared across the resistors. This example assumes ideal wires and a source with negligible internal resistance.
Original explanation prepared with AI assistance.
Lees hierdie verduideliking in AfrikaansWhat you will practise
Calculate total series resistance, current and voltage distribution.
The method
Add the resistances, use the supply voltage to find current, then calculate each resistor’s potential difference.
Worked example
A 12 V ideal supply connects 2 Ω and 4 Ω resistors in series. Find the current and voltage across each resistor.
- Rtotal = 2 + 4 = 6 Ω.
- I = V/R = 12/6 = 2 A through both resistors.
- V₂Ω = 2(2) = 4 V and V₄Ω = 2(4) = 8 V.
- Check: 4 + 8 = 12 V, equal to the supply voltage.
Common mistake
Do not split the current between components in series; there is only one path.
Try it yourself
A 9 V ideal supply connects 1 Ω and 2 Ω resistors in series. Find the current.
Show the explained solution
Rtotal = 3 Ω, so I = 9/3 = 3 A.
Curriculum and sources
Use the official CAPS subject document and your teacher’s annual plan to confirm the sequence and scope for your class. The link below is an official reference, not evidence of DBE approval of this explanation.
DBE: CAPS for the FET phaseFind your next lesson
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