Series circuits · Year 11
In Year 11 you get fluent with: adding resistances in series and sharing p.d. between resistors in series.
In a series circuit everything is in one loop. The same current flows everywhere, the supply's p.d. is shared between the components, and the resistances add up. If one part breaks, the whole loop stops.
Key facts
- In series, the bigger resistor gets the bigger share of the p.d.
Worked examples
Example 1
Resistors of 3 Ω, 5 Ω and 4 Ω are in series. What is the total resistance?
Answer: 12 Ω
Example 2
A 6 V battery is connected to 10 Ω and 20 Ω resistors in series. What current flows?
Answer: 0.2 A
Example 3
A 12 V battery is connected to 4 Ω and 2 Ω resistors in series. Find the current and the p.d. across each resistor.
Answer: 2 A; 8 V and 4 V
Example 4
A 12 V supply is connected across 3 kΩ and 1 kΩ resistors in series. Find the p.d. across the 3 kΩ resistor without working out the current.
Answer: 9 V