How does a quiz-show buzzer know when to sound? What must happen in the wires for it to ring only at the right moment?
Hands up: what job do you think a switch does in a circuit?
How could two pieces of foil act as a switch for a quiz buzzer?
A switch opens or closes a gap so electricity can flow or stop. Without a complete path, nothing works.
A closed loop is a full path from one side of the battery, through the parts, and back again with no gaps.
Look at the foil (or the kit if your teacher holds it up). Those metal surfaces can be contact points: they touch only when you want the circuit on, and that touch is the switch.
On the board we will build a loop that includes a battery, a buzzer and a switch. Call out where each part should go so the buzzer sounds only when the switch is closed.
What happens if we open the switch?
Plan a switch-and-buzzer loop
Plan a switch-and-buzzer loop
Before the kit comes out, put these build steps in a sensible order on the board. Call out which should come first, then next:
- Connect the battery in the holder
- Join wires to make most of the loop
- Leave one gap with two contact points
- Add the buzzer or bulb in the loop
- Touch the contacts to close the gap and check the output
When you build, use this order as your checklist. If the buzzer never sounds, which step is probably missing? If it never stops, which step fails?
In your group, build a circuit that does a job. Choose a quiz buzzer or a steady-hand game.
Quiz buzzer: stick two foil pads on card so they sit as a gap in the loop. One pad links toward the battery path and the other toward the buzzer. A foil-wrapped paperclip wand closes the loop only when it touches both pads at once. Wrong pads stay open (no path).
Steady-hand: a bent paperclip or wire track is one side of the gap; a looped wand is the other. When the wand touches the track, the loop closes and the buzzer sounds.
Your circuit must use a battery, wires, a buzzer or bulb, and two contact points that touch only when you want it on. Use the ordered steps on the board as your checklist while you build and test.
If your circuit will not work, rebuild it on the board planner first and find the break in the loop, then go back to the kit.
Check your quiz-buzzer loop
Check your quiz-buzzer loop
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