Boxi Learn › Physics › Stage 3 · Structure and Evidence
Is current used up in a bulb?
Current is used up by a bulb.
The current is the same all the way round a series loop: a bulb turns energy into light and heat, it does not use up charge. In parallel each branch gets the full battery voltage and the branch currents add up.
A friend says the first bulb after the battery's + end gets the most current, so it shines brightest. Using the words “loop”, “current” and “energy”, explain why bulbs in one series loop are equally bright.
With a school circuit kit (a battery, two small bulbs, wires), connect the bulbs in a line, then side by side, and compare how bright they are. No kit? Notice that switching one lamp off at home does not switch the others off — home lamps are wired in parallel. Never open mains wiring.