Electric Current
Electric Current is the flow of tiny charged bits through a wire, like water moving through a hose.
Water flows through a garden hose when you open the tap. In a wire, tiny charged bits called electrons move the same way, from one end to the other. A battery pushes the electrons forward, just like water pressure pushes water through the hose. More electrons moving past a point each second means a stronger current.
Explaining electric current by grade level
When you touch both ends of a wire to a battery, something starts to move inside the metal. Tiny bits too small to see flow through the wire. That flow is what lights up a bulb. The more bits that flow, the brighter the bulb gets.
Projects that explore electric current
A wire's temperature changes how easily current flows through it. You wind 5 meters of thin copper wire around a PVC pipe, connect it to a 4.5V battery pack, and track the current with an ammeter while an ohm meter measures resistance. As charged bits flow through the wire, the wire heats up. Every 10°C rise, you record both readings. The data tells a clear story: resistance climbs steadily as the wire gets hotter, and the ammeter shows the current dropping in response.
Heat slows the flow of charged bits through a wire — and this experiment makes that pattern visible. You wind copper wire around a PVC pipe, connect it to three 1.5V batteries, and measure current with an ammeter while an infrared thermometer tracks the wire's temperature. Every 10°C rise, you also read the resistance with an ohm meter. As the wire heats up, resistance climbs steadily and the current drops in step with it.
For current to flow, charged bits need a path through the material. You set up two beakers with copper electrodes — one filled with distilled water, one with sea water — then complete each circuit with a battery, a light bulb, and an ammeter. The voltage stays nearly the same in both beakers. The current, however, jumps from almost zero in distilled water to a level that lights the bulb in sea water. Dissolved salt ions give sea water its conducting power; distilled water has none of them, so charged bits have no way through.
The current flowing into a motor tells you how hard it is working, even when it has nothing to drive. You run four DC servomotors — ranging from 30 to 100 watts — with no load, measuring the voltage and current at each motor's input with a multi meter and an ammeter. Then you cut the power and time how long each motor takes to stop. Bigger motors have larger moving parts and more friction, so more charged bits must flow through the wire to keep them spinning. That extra current shows up directly in the input power measurement.