Electricity and Circuits Property Voltage (V) Current (I ) Resistance (R) Power (P) Units of Measure Volts (V) Amps (A) Ohms (Ω) Watts (W)
Electric Circuits An electric circuit is a network of electrical components (resistors, transmission lines, electrical sources, switches, etc.) that forms a closed loop and provides a path for electrical energy. Circuits have three basic parts: –An energy source that converts non-electrical energy into electrical energy; examples are batteries and generators. –An output device that uses electrical energy to do work; examples are motors, lamps, and displays. –Materials to make a connection to allow electrical energy to flow; examples are wires and cables
Examples of Symbols for Circuit Diagrams Component SymbolFunction of Component WireTo pass current from one part of a circuit to another Wires joined A dot should be drawn to show where two wires join together. BatterySupplies electrical energy; the larger terminal is positive (+) Light Bulb and SocketConverts electrical energy to light energy ResistorRestricts the flow of current On-Off SwitchAllows current to flow only when it is in the on (closed) position +-
Series Circuits Electrical components connected in series are connected along a single path so the current only has one path to follow. If one component in a series circuit is disconnected or fails, the entire circuit is turned off. battery switch Bulb A Bulb B In the circuit to the left, what would happen if Bulb B burned out? If Bulb B burned out there would be no way for the electrical energy to flow. Bulb A would not light.
Parallel Circuits battery Bulb ABulb BBulb C Electrical components connected in parallel are connected so that the current has multiple paths that it can take. If one component in a parallel circuit is removed or fails, the other components will still have an intact path for current and will continue to work.
Review Activity – Circuits Answer the questions on the Review Sheet. After you have finished, your teacher will help you check your answers using this animation. Batteries Switch ASwitch BSwitch CSwitch D Bulb ABulb BBulb CBulb D
Resistors A resistor is a component that restricts the flow of current. Resistance is measured in ohms. The symbol for the ohm is (omega). On a circuit diagram, resistors are represented by 2 4