What happens to a resistor with an even smaller resistance? Just how much can a resistor heat up? A incandescent light bulb will show you.

In an incandescent lamp bulb you find a **thin wire**
having a resistance of only a **few ohms**.
In the circuit, the wire heats up so much by the current flowing
through that it starts to **glow**.

How much current flows through a resistor at a fixed voltage
is described by **Ohm's law**.
How much heat is generated at a resistor is described by
**Joule's law**.

In the next steps are you looking at what changes in a circuit if you use multiple resistors.