One loop: the same current everywhere, the supply p.d. shared out, and resistances that add.
What you will learn
- State the rules for current, p.d. and resistance in series
- Calculate the total resistance and the current in a series circuit
- Work out how the p.d. is shared between components
The three series rules
In a series circuit everything is in one loop.
There are no junctions: points where a wire splits into two or more paths.
- Current: the same at every point. The ammeter would read the same anywhere in the loop.
- Potential difference: the supply p.d. is shared between the components: V₁ + V₂ = supply p.d.
- Resistance: the total is the sum.
total resistance = R₁ + R₂ + ...
Rtotal = R₁ + R₂
This one is not given on any sheet: learn it.
The rest of this lesson and its 7 practice questions are locked.
In this lesson
- The three series rules
- Working through a series circuit
- Try it: Share the p.d. in the simulation
7 practice questions, marked as you go; about 20 minutes in all.
In this unit: Electric circuits
Circuit symbols, charge and current, V = IR, I-V graphs, series and parallel circuits, and sensing circuits with LDRs and thermistors.