Sara wires a torch circuit and puts the switch on the wire between the two cells, not next to the…
Sara wires a torch circuit and puts the switch on the wire between the two cells, not next to the bulb. Dev says a switch will not work there; it has to be right before the bulb. Sara says anywhere in the loop is fine. Who is right?
Who do you think is right? Pick one.
The answer: Sara is right
Why
Dev's picture makes a kind of sense: the switch 'guards' the bulb, so it feels like it should stand right next to it. But a circuit is a single closed loop, and a switch works by breaking that loop; once the ring is open at any point, no current flows anywhere in it. Where you put the gate in a closed fence does not matter, because opening it anywhere stops everything from getting round. Picture a ring of people passing buckets hand to hand: if any two let go, the chain stops, whichever pair it was. Test: move the switch to three different spots in the same loop and it turns the bulb on and off identically from each. Sara is right: a switch controls the whole loop from any point on it.
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