To show how a resistor and LED are wired to emit light.
Build the circuit shown on the left by placing all the parts with a black 1 next to them on the base grid first. Then, assemble parts marked with a 2.
When you close the slide switch (S1), current flows from the batteries (B1) through the slide switch, through the resistor (R1), through theLED (light emitting diode, D1) and back to the battery. The closed slide switch completes the circuit. The resistor limits the current andprevents damage to the LED. NEVER PLACE AN LED DIRECTLY ACROSS THE BATTERY! If no resistor is in the circuit, the battery may push enough current through the LED to damage the semiconductor that is used to produce the light. LEDs are used in all types of electronic equipment to indicate conditions and pass information to the user of that equipment.
Can you think of something you use everyday that has an LED in it?