A direct‑current (DC) circuit is composed of four essential elements: a power source, conductors, a control switch, and a load. In this hands‑on tutorial we’ll use a D‑cell battery, wires, paper clips, and a small light bulb to demonstrate how these parts work together.
Strip about half an inch of insulation from each end of the two wires.
Secure one stripped end to the battery’s positive (+) terminal. Wrap the other end around one end of the first paper clip.
Insert a thumbtack or nail through the cardboard so the paper clip can pivot freely—this will act as the switch.
Straighten the second paper clip. Place one end on the cardboard near the first clip, but not through it. This is the contact point; when the switch touches it the circuit closes.
Wrap the free end of the second paper clip around the positive side of the light bulb and secure it with tape if needed.
Tape the other wire’s stripped end to the bulb’s negative contact, then attach the free end to the battery’s negative (-) terminal.
Secure the battery and bulb to the cardboard with tape so they stay in place.
Move the paper‑clip switch to touch the contact point; the bulb should illuminate.
Any bulb with two contacts—either a metal dot at the base or two metal blades—will work for this demonstration.
Do not disassemble the battery. Follow all precautions on the battery packaging and never dispose of it in a fire.
