1. 16.3 Resistance and Ohm’s Law

2. Electrical Resistance
Resistance: how strongly a wire or other object resists current flowing through it
low resistance = large current
high resistance = little current

3. Electrical Resistance
Every electrical device is designed with a resistor that causes the right amount of current to flow when the device is connected to voltage.
A light bulb’s resistance increases when there is more current because the bulb gets hotter when more current passes through it.

4. Measuring Resistance
Resistors are used to control the current in circuits.
Resistance is measured in ohms (Ω)

5. Measuring Resistance Two types of resistors:
1. Fixed resistor: resistance cannot be changed
2. Variable resistor (potentiometer): resistance can be adjusted

6. Conductors and Insulators
Conductor: a material with low electrical resistance
examples: metals
Insulator: a material with high electrical resistance
- examples: rubber, plastic

7. Ohm’s Law
Static electricity: less than one millionth of a coulomb
The total amount of resistance in a circuit determines the amount of current in the circuit for a given voltage.

8. Ohm’s Law
Static electricity: less than one millionth of a coulomb

9. Ohm’s Law Exit Slip
A toaster oven has a resistance of 12 ohms and is plugged into a 120-volt outlet. How much current does it draw?