# Electric Current

## Physical Science - Middle School

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Electric Current © Copyright NewPath Learning. All Rights Reserved. 94-4407 Visit www.newpathlearning.com for Online Learning Resources. What is Electric Current? The continuous flow of electric charges through a wire or similar material is called electric current. Imagine electric charges moving at a steady rate through a wire. You can count how many charges move past a given point during a certain period of time. If the charges start to flow more quickly, you would count more charges moving past the same point over the same amount of time. Therefore, the rate of flow, or the rate of the current, has increased. Current is Measured in Amps The rate of flow of electrical charges, or current, is expressed in amperes, or amps. The capital letter A is used to symbolize this unit. In equations, amps are symbolized by the capital letter I. 5 0 10 15 20 25 30 35 40 45 50 55 electric current point B point A rate of ow = amount of charges time Quantity Measurement Current I amp A Unit Symbol Unit of Measure Formula Abbreviation 5 0 10 15 20 25 30 35 40 45 50 55 electric current point B point A rate of ow = amount of charges time Quantity Measurement Current I amp A Unit Symbol Unit of Measure Formula Abbreviation DC direct current AC alternating current AC alternating current Two Types of Electrical Current There are two types of electric current, DC and AC. The charges in DC, or direct current, always flow in the same direction. The charges in AC, or alternating current, flow one way and then flow the other way. They are continuously reversing direction. Many batteries use DC electricity. Electric appliances around the house such as microwaves, televisions and washing machines use AC electricity. The electrical power is supplied using alternating current because it is easier to safely control the voltage of this type of current. Electricity in Circuits An electric circuit is a complete path that electricity flows through. For electrical current to continuously flow, the charges must move through a path that is unbroken. This continuous flow of current within a circuit enables us to use electrical power. Our homes and machines use a variety of electric circuits. V 0 10 20 30 electric current point B point A Quantity Measurement Voltage V volt V Unit Symbol Unit of Measure Formula Abbreviation Voltage Voltage is the potential difference between two points in a circuit. Another way to think about it, is the amount of energy released as a charge moves between these two points. Voltage is measured in units called volts. In equations voltage is symbolized by the letter V. zinc electrode carbon electrode electrolyte paste negative terminal positive terminal Dry cell + + + 1.5 volt 12 volt 1.5 volt 12 volt The greater the voltage is, the higher the current. A 1.5-volt battery used in a camera produces less electrical current than a 12-volt battery used in a car.
Pause and Review Fill in the ovals that are labeled with appropriate details. For the ovals that are not labeled, provide both a label and details. © Copyright NewPath Learning. All Rights Reserved. 94-4488 Visit www.newpathlearning.com for Online Learning Resources. Electric Current Power Voltage Electricity DC usage storage type of circuits ____________________________ ___________________ ____________________________ ___________________ ____________________________ ___________________ ____________________________ ___________________ ____________________________ ___________________ ____________________________ ___________________ ____________________________ ___________________ ____________________________ ___________________ ____________________________ ___________________ ____________________________ ___________________ ____________________________ ___________________ Electricity