Series and Parallel Circuits
≈ 20 minThere are two ways to connect several components to one cell.
Series — the components are joined one after another in a single loop. There is exactly one path for the current.
Parallel — the circuit splits into branches and joins again. There is more than one path for the current, and each component sits on its own branch.
| Series | Parallel | |
|---|---|---|
| Number of paths | One | One per branch |
| Remove or blow one globe | Every globe goes out | Only that branch goes out |
| Add more globes | All the globes get dimmer | Each branch stays about as bright |
| Switching | One switch controls everything | Each branch can have its own switch |
The reason series globes dim as you add more is that the one cell must now share its energy among more components. In parallel, each branch is connected straight across the cell, so each one gets the full push.
Worked example. Three identical globes are connected to one cell, first in series and then in parallel. In each case, globe 2 is unscrewed. What happens?
- Series: unscrewing globe 2 breaks the single loop. There is now no complete path, so globes 1 and 3 go out as well. All three are dark.
- Parallel: globe 2's branch is broken, but the branches carrying globes 1 and 3 are still complete loops back to the cell. Globe 2 goes out; globes 1 and 3 stay on, just as bright as before.
This single test — remove one component and see what survives — is the fastest way to tell the two arrangements apart.
Three globes are connected in series with one cell. One of the globes blows. What happens to the other two?
Which type of circuit — series or parallel — is used to wire the lights in a house, so that one blown globe does not switch off all the others?
A circuit has one cell and one globe. Two more identical globes are then added in series with the first. What happens to the brightness of the globes?
Five identical globes are connected in parallel across one battery, each on its own branch. Two of the globes blow. How many globes are still shining?