Secret resistance

Resistors aren't the only electronic components with resistance... in fact, everything electric current has to flow through has some resistance. Here's a Project that will let you see this "serect resistance" for yourself.

Look at the schematic for this Project. It would seem like the electricity from the Batteries would simply flow through the Relay's coil and light the Lamp- But when you build this Project, you'll notice that the Lamp will not light. The only way to get the Lamp to light is to press the Key.

This is because the resistance of the wire in the Relay's coil prevents enough current from flowing to the Lamp. Pressing the Key completes an easier path for the electricity' and causes the Lamp to light. We sometimes say electronic devices have a loss when connected in a circuit. This means the resistance of the item is high and uses some of the electricity in the circuit. "Lossy" electronic parts often give off heat, since an item with high resistance converts electricity to heat

(Now that you have that bit of information, how do you suppose an electric stove or heater works?)