How to play Room Wiring
- Choose a test and read the branches and the supply on the card.
- Each branch gets the full voltage: find each current with I = V ÷ R and add them, or use 1/R = 1/R₁ + 1/R₂.
- Type your prediction and press Start. The branches switch on in turn and the meters follow.
- Compare the ammeters and the graph with your orange prediction.
Parallel circuits
In a parallel circuit each branch connects straight across the supply, so every branch gets the full supply voltage and works on its own: it draws I = V ÷ R whatever the others do. The main current is the sum of the branch currents, so each extra branch adds current and the combined resistance falls: 1/R = 1/R₁ + 1/R₂ + …, always less than the smallest branch. That is how homes are wired. Every socket and lamp gets the full mains voltage, switching one off leaves the rest working, and an unplugged lamp simply stops drawing its share. But every appliance switched on adds to the current in the main cable, which is why a breaker trips when too much is on at once.
A focused learning model
The supply is steady, the wires and ammeters are ideal, and each branch draws its current the moment its switch closes. The branches switch on in turn over 2 s, branch k of n at 2·k ÷ n s, and the run ends at 3 s; in the unplug test one lamp is unplugged at 2.5 s. The breaker trips the moment the main current passes 16 A (a current within 0.05% counts as holding), turning every branch off; each lamp draws 0.50 A from 230 V. Teaching values, not safety limits: never work on mains wiring. The electron dots move at a speed in step with the current, not at the real drift speed. Answers within 2% are right; the breaker test needs the exact most whole number.