Science Puzzle
Which Bulb Burns Brighter?
Two circuits, each with the same battery and the same two bulbs. In Circuit A the current must pass through one bulb then the other, all in a single loop. In Circuit B the current splits and each bulb sits on its own branch.
Which arrangement makes the bulbs glow brighter, and what happens if you unscrew one bulb?
The Answer
Circuit B, the parallel one, and its bulbs stay lit independently. Think of the battery as providing a fixed electrical push. In series, the two bulbs must divide that push between them, so each receives only half and both glow dimly. In parallel, each branch is connected straight across the battery, so every bulb receives the full push and burns at full brightness.
The unscrewing test is the clinching difference. In series there is only one path, so removing a bulb breaks the loop and the other bulb dies too. This is why old Christmas tree lights all went out when a single bulb failed. In parallel each branch is its own route, so unscrew one bulb and the other carries on happily. That is exactly why the lights in your house are wired in parallel: switching off the kitchen light must not black out the hallway.
The parallel circuit does drain the battery faster, because it draws more total current. Brightness has a price.
The principle: Series and parallel circuits. Components in series share the supply voltage and depend on one another; components in parallel each receive the full voltage and work independently.