Electronics bench
Step 1 of 8
Close the circuit
Why nothing happens until the loop is complete
Electricity does not get used up at the LED. It leaves the supply at +, travels all the way round, and comes back in at −. If any part of that path is missing, nothing moves anywhere — not even in the part that is connected.
The supply, a resistor and an LED are already on the bench, and most of the wiring is done. One join is missing.
Tap a terminal, then tap another, to join them.
One leg of Supply is not joined to anything. Current has to leave the supply, go all the way round, and come back — a loose end stops it.