Resistance is a term used in current electricity to describe things like light bulbs, motors, heaters, stereos, etc. All of these things are called Loads and convert the energy the coulombs carry, into other forms.

In the wooden block model, resistance can be thought of as how hard it is to make things spin around. Things with a lot of resistance need a lot of energy to make them spin around. Things with little resistance don't need very much energy at all to make them spin. In this model this energy is represented by the total distance the Coulomb blocks have to drop before the load can spin around.

In the flowing water model, resistance can be thought of as gravel (or water wheels) in the pipes. Pipes with a lot of resistance don't let the water flow through very easily. They use the water pressure to move the water wheels (or gravel) around.

In both models Resistance makes it hard for the Coulombs to flow. Resistance is often described as an opposition to the flow of current. The energy used to get current to flow through the resistance is converted to heat (on an electric stove element) or light (in a bulb filament)

Resistance is measured in units called ohms (S).

Joke: The electric stove gets hot because there are "Ohms on the Range".

Student Activity -Total Resistance of Loads Connected in Series and Parallel

Student Activity    

Total Resistance / Swizzle Stick Activity

Give each student three "Swizzle Stick" type plastic straws and a small section of masking tape. Have the students blow through one straw. Then have them tape the straws together in line (series). Have the students blow through them again. Have them remove the tape, and hold the straws side by side (parallel). Have the students blow through them again.

 Questions