23.2. Electric Current http://www.ck12.org
- Electric current occurs whenever there is a difference in electric potential energy, or voltage. Voltage is
measured in volts (V). - Sources of voltage include electric generators and cells. Electric generators change kinetic energy to electrical
energy. Chemical cells change chemical energy to electrical energy, and solar cells change solar energy to
electrical energy. - Electric current needs a material through which to travel, but particles of the material may resist the flow of
current. Materials differ in how much they resist electric current. Materials with low resistance are called
electric conductors, and materials with high resistance are called electric insulators. - According to Ohm’s law, current increases when voltage increases or resistance decreases. Current can be
calculated as voltage divided by resistance.
Lesson Review Questions
Recall
- What is electric current?
- What is the difference between direct and alternating current?
- Define voltage.
- List three sources of voltage.
- Identify three properties that affect the resistance of a given material.
Apply Concepts
- A 12-volt battery is connected to a light bulb by wires. The wires and light bulb together have 6 ohms of
resistance. How many amps of current are flowing through the wires?
Think Critically
- Explain how voltage is related to electric current.
- Compare and contrast electric conductors and electric insulators. Give an example of each.
Points to Consider
In this lesson, you learned about electric current. The next lesson, "Electric Circuits," focuses on the path that electric
current travels. Think about a ceiling light with a wall switch. You probably have several in your home.
- What path does current travel to get from the switch on the wall to the light on the ceiling?
- How do you think the switch controls the flow of current to the light?