In the model illustrated by the animation, a battery provides the electromotive force that draws a current through a circuit. The electromotive force is represented by a battery, and a battery with a larger voltage possesses a larger electromotive force. Current is represented in the model by the speed of the charges moving through the circuit and resistance is represented by the section of the model containing baffles.
In the first segment, the circuit is open. No current is able to flow because the break in the wire represents infinite resistance.
In the second segment, the circuit is closed and charges flow, creating a current.
In the third segment, the voltage of the battery increases and the greater force causes the current to increase. According to Ohmís law, doubling the voltage with double the current for the same constant resistance.
In the fourth segment, more baffles are added to the resistor which impedes the motion of the charges and decreases the current. According to Ohmís law, doubling the resistance at constant voltage reduces the current by half.
- Electrical power is the rate at which energy is expended in a circuit. Based on the model shown in the animation, what probably happens to the electrical energy in a real resistor?
- Explain why a toaster can be thought of a just one big resistor.
- Where does the electrical power of a light bulb go? Would you expect a light bulb to have a higher or lower resistance compared to a toaster? Why?
- Many sizes of batteries may have the same voltage. For example. ďDĒ cells and watch batteries may both be rated at 1.5 volts. How are different types of batteries with the same voltage rating different? (Hint: batteries store electrical potential energy. Is potential energy the same thing as voltage?)