Chapter 20Chapter 20

ElectricityElectricity

Chapter 20Chapter 20

*Electric charge- property that causes *Electric charge- property that causes subatomic particles such as protons and subatomic particles such as protons and electrons to attract or repel each otherelectrons to attract or repel each other two types; positive and negativetwo types; positive and negative

An excess or shortage of electrons An excess or shortage of electrons produces a net electric charge.produces a net electric charge.

Like charges repel, and opposite charges Like charges repel, and opposite charges attract.attract.

*Electric force- the attraction or *Electric force- the attraction or repulsion between electrically charged repulsion between electrically charged objectsobjects

Chapter 20Chapter 20 *Electric field- effect an electric charge *Electric field- effect an electric charge

has on other charges in the space around has on other charges in the space around itit

The strength of an electric field depends The strength of an electric field depends on the amount of charge that produces on the amount of charge that produces the field and on the distance from the the field and on the distance from the charge.charge.

*Static electricity- study of the behavior *Static electricity- study of the behavior of electric charges, including the transfer of electric charges, including the transfer of charges between objectsof charges between objects

Charge can be transferred by friction, by Charge can be transferred by friction, by contact, and by induction.contact, and by induction.

Chapter 20Chapter 20

*Law of conservation of charge- *Law of conservation of charge- total charge in an isolated system is total charge in an isolated system is constantconstant

*Induction- transfer of charge *Induction- transfer of charge without contact between materialswithout contact between materials

Static discharge occurs when a Static discharge occurs when a pathway through which charges can pathway through which charges can move forms suddenly. (Lightning)move forms suddenly. (Lightning)

Chapter 20Chapter 20

*Electric current (*Electric current (II)- continuous flow )- continuous flow of electric charge; measured in of electric charge; measured in amperes, or amps (A) = 1 C per amperes, or amps (A) = 1 C per secondsecond

*Electrical conductor- material *Electrical conductor- material through which charge can flow easilythrough which charge can flow easily

*Electrical insulator- material *Electrical insulator- material through which charge cannot flow through which charge cannot flow easilyeasily

Chapter 20Chapter 20

*Resistance (*Resistance (RR)- opposition to )- opposition to the flow of charge in a material; the flow of charge in a material; measured in ohms measured in ohms A material’s thickness, length, and A material’s thickness, length, and

temperature affect its resistance.temperature affect its resistance. More resistance, more heat.More resistance, more heat.

Chapter 20Chapter 20

In order for charge to flow in a In order for charge to flow in a conducting wire, the wire must be conducting wire, the wire must be connected in a complete loop that connected in a complete loop that includes a source of electrical includes a source of electrical energy.energy.

*Potential difference- difference in *Potential difference- difference in electrical potential energy between electrical potential energy between two places in an electric field; two places in an electric field; measured in volts (V); considered measured in volts (V); considered voltage*voltage*

Chapter 20Chapter 20

*Ohm’s Law- voltage in a circuit equals *Ohm’s Law- voltage in a circuit equals the product of the current and the the product of the current and the resistanceresistance

FORMULA (Ohm’s Law)FORMULA (Ohm’s Law) V = I · R V = I · R oror I = I = VV

RR Increasing the voltage increases the Increasing the voltage increases the

current. Keeping the same voltage and current. Keeping the same voltage and increasing the resistance decreases the increasing the resistance decreases the current.current.

Chapter 20Chapter 20

*Electric circuit- complete path through *Electric circuit- complete path through which charge can flowwhich charge can flow

Circuit diagrams use symbols to represent Circuit diagrams use symbols to represent parts of a circuit, including a source of parts of a circuit, including a source of electrical energy and devices that are run electrical energy and devices that are run by the electrical energy.by the electrical energy.

If a switch is open, the circuit is not a If a switch is open, the circuit is not a complete loop, and current stops. This is complete loop, and current stops. This is an open circuit. If the switch is closed, an open circuit. If the switch is closed, the circuit is complete and charge can the circuit is complete and charge can flow, creating a closed circuit.flow, creating a closed circuit.

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*Series circuit- charge has only one *Series circuit- charge has only one path through which it can flow. path through which it can flow. If one element stops functioning in a If one element stops functioning in a

series circuit, none of the elements can series circuit, none of the elements can operate.operate.

*Parallel circuit- electric circuit with *Parallel circuit- electric circuit with two or more paths through which two or more paths through which charges can flow.charges can flow. If one element stops functioning in a If one element stops functioning in a

parallel circuit, the rest of the elements parallel circuit, the rest of the elements still can operate.still can operate.

Chapter 20Chapter 20 *Electric power- rate at which *Electric power- rate at which

electrical energy is converted to electrical energy is converted to another form of energy; measured in another form of energy; measured in joules per second, or watts (W) (kW)joules per second, or watts (W) (kW)

Electric power can be calculated by Electric power can be calculated by multiplying voltage by current.multiplying voltage by current.

FORMULA (Electric power)FORMULA (Electric power) P = power (W); I = current (A); V = P = power (W); I = current (A); V =

voltage (V)voltage (V) P = I · VP = I · V

Chapter 20Chapter 20

Correct wiring, fuses, circuit Correct wiring, fuses, circuit breakers, insulation, and breakers, insulation, and grounded plugs help make grounded plugs help make electrical energy safe to use.electrical energy safe to use.

*Grounding- transfer of excess *Grounding- transfer of excess charge through a conductor to charge through a conductor to Earth is called groundingEarth is called grounding