If you're seeing this message, it means we're having trouble loading external resources for Khan Academy.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

resistance

4 videos
Exploring materials which cause a decrease in deflection when added in series with our meter.

Series load

VIDEO 1:12 minutes
Why does the deflection change when an electromagnet is attached to the circuit? Does it matter what side of the electromagnet we test?

Pencil resistor

VIDEO 1:04 minutes
A pencil causes a change in the deflection, similar to the effect of adding an electromagnet. Why?

Variable resistor (pencil)

VIDEO 1:28 minutes
We use the inside of a pencil (graphite) to apply different "lengths of pencil" to the circuit. What relationship do you observe between length of graphite and deflection angle?

Listen to variable resistance

VIDEO 1:11 minutes
Here we draw a line on a page and use it as a variable resistor in series with a speaker. What relationship do we hear? Does it sound linear?