<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
You are viewing an older version of this Concept. Go to the latest version.

# Electric Circuits

## A closed loop through which current can flow.

%
Progress

MEMORY METER
This indicates how strong in your memory this concept is
Progress
%
How Can You Resist?

### How Can You Resist?

Credit: Tylercat5
Source: http://commons.wikimedia.org/wiki/File:MV_Lamp_175_W.JPG

Do you see the small blue and silver cylinder near the bottom of this mercury-vapor light bulb? It’s an electrical device called a resistor.

#### The Back Story

• A resistor is a device used to regulate the amount of electric current in a circuit. Resistors are used in light bulbs and appliances to limit the amount of current that reaches them. They work by resisting the flow of current through the circuit.
• Resistors come in different sizes. Which size does a device need? You can use Ohm’s law to find out.
• Ohm’s law states the relationship among voltage, current, and resistance in a simple electric circuit. For a better understanding of these relationships, experiment with this applet: http://www.physics.uoguelph.ca/phyjlh/Fendt/phe/ohmslaw.htm

#### Can You Apply It?

1. State Ohm’s law and represent it with a formula.
2. What SI units are used for the variables in the formula for resistance in question 1?
3. How many ohms of resistance does a resistor need to provide for a 12-volt circuit to carry 6 amps of current?
4. How much current does a 120-volt circuit carry if it contains a resistor that provides 10 ohms of resistance?
5. What do you think might happen to an appliance in a circuit if the wrong resistor is used so the appliance gets too much current?

### Notes/Highlights Having trouble? Report an issue.

Color Highlighted Text Notes