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Current and Circuits. Section 22.1 Physics. Objectives. Define and electric current and the ampere. Describe conditions that create current in an electric circuit. Draw circuits and recognize that they are closed loops. Define power in electric circuits.
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Current and Circuits Section 22.1 Physics
Objectives • Define and electric current and the ampere. • Describe conditions that create current in an electric circuit. • Draw circuits and recognize that they are closed loops. • Define power in electric circuits. • Define resistance and describe Ohm’s Law.
Producing Electric Current • Electric Current: the flow of charged particles. • We show the path of electric currents by illustrating Electric Circuits: A closed loop, or continuous path, through which electric charges flow.
The Production of Electric Energy • How is electric energy produced? • Usually a generator is hooked up to a mechanical energy source. • The generator converts mechanical energy into electrical energy by using electromagnetic induction.
The Production of Electric Energy • Once the generator has created electric energy, a step-up transformer increases the amount of current that leaves through the power lines. • These power lines run to your home. • Once the electrical energy has reached your home, a step-down transformer decreases the amount of energy.
The Production of Electric Energy • But how do we measure all the energy that is traveling through the power lines and through your homes electrical wiring? • We use Ohm’s Law: V= IR • Voltage (volts) equals current (ampere) times resistance (ohms, Ω).
Determining Power • We can also determine the amount of power running through a wire. • P = IV • Power (watts, w) equals current times voltage.
Practice Problems • Pg 511 • 1-4 • Pg 515 • 5-10
Diagraming Circuits • Pg 515: Circuit Symbols. • You will need to become very familiar with these symbols. • Follow the steps on pg 516. • Practice Problems • Pg 517 • 11-13