Electronics basics: open or closed?

Meet a tiny circuit

Look at our picture of a simple circuit. It has a cell, wires, a switch, and a lamp. A cell is an energy source. The wires connect the parts. Today we are picture detectives. We will not build or touch a real circuit.

Follow the whole path

Start at one end of the cell. Follow the line through the switch and the lamp, then back to the other end of the cell. A complete path lets current flow in this simple circuit. Every connection along that path matters.

A gap stops the flow

Picture A has an open switch. Open means there is a gap in the path. In our simple circuit, current cannot keep flowing around that gap. The lamp is off. The switch is not being rude to the lamp. It is simply making a break.

Close the gap

Picture B has a closed switch. The switch joins the two sides, so the path is complete. With a working cell and lamp, current flows and the lamp lights. Closed means connected here. It does not mean putting the lamp inside a closed box.

Pause and predict

Imagine our lamp is glowing in picture B. Now imagine a gap appears in one wire. Do not change a real wire; change only the picture in your mind. Pause and predict whether the lamp would stay on or turn off.

Check the path again

The lamp turns off in this simple model. Even though the switch is still closed, the new gap breaks the complete path. To explain your answer, point to the gap. A good circuit detective checks the whole path, not just the switch.

A different kind of light

Fun fact: an LED makes light without heating a wire filament until it glows. Our lamp picture is a simple starting point; real lights can work in different ways. Never use wall outlets for this activity, and never put batteries in your mouth.

Your turn to trace

Say the difference out loud: an open switch makes a gap, and a closed switch connects the path. Now continue to the worksheet. Trace each picture, decide whether its path is complete, and explain why its lamp would be on or off.