# Chapter 20 Electricity.

## Presentation on theme: "Chapter 20 Electricity."— Presentation transcript:

Chapter 20 Electricity

Chapter 20 *Electric charge- property that causes subatomic particles such as protons and electrons to attract or repel each other two types; positive and negative An excess or shortage of electrons produces a net electric charge. Like charges repel, and opposite charges attract. *Electric force- the attraction or repulsion between electrically charged objects

Chapter 20 *Electric field- effect an electric charge has on other charges in the space around it The strength of an electric field depends on the amount of charge that produces the field and on the distance from the charge. *Static electricity- study of the behavior of electric charges, including the transfer of charges between objects Charge can be transferred by friction, by contact, and by induction.

Chapter 20 *Law of conservation of charge- total charge in an isolated system is constant *Induction- transfer of charge without contact between materials Static discharge occurs when a pathway through which charges can move forms suddenly. (Lightning)

Chapter 20 *Electric current (I)- continuous flow of electric charge; measured in amperes, or amps (A) = 1 C per second *Electrical conductor- material through which charge can flow easily *Electrical insulator- material through which charge cannot flow easily

Chapter 20 *Resistance (R)- opposition to the flow of charge in a material; measured in ohms A material’s thickness, length, and temperature affect its resistance. More resistance, more heat.

Chapter 20 In order for charge to flow in a conducting wire, the wire must be connected in a complete loop that includes a source of electrical energy. *Potential difference- difference in electrical potential energy between two places in an electric field; measured in volts (V); considered voltage*

Chapter 20 *Ohm’s Law- voltage in a circuit equals the product of the current and the resistance FORMULA (Ohm’s Law) V = I · R or I = V R Increasing the voltage increases the current. Keeping the same voltage and increasing the resistance decreases the current.

Chapter 20 *Electric circuit- complete path through which charge can flow Circuit diagrams use symbols to represent parts of a circuit, including a source of electrical energy and devices that are run by the electrical energy. If a switch is open, the circuit is not a complete loop, and current stops. This is an open circuit. If the switch is closed, the circuit is complete and charge can flow, creating a closed circuit.

Chapter 20 *Series circuit- charge has only one path through which it can flow. If one element stops functioning in a series circuit, none of the elements can operate. *Parallel circuit- electric circuit with two or more paths through which charges can flow. If one element stops functioning in a parallel circuit, the rest of the elements still can operate.

Chapter 20 *Electric power- rate at which electrical energy is converted to another form of energy; measured in joules per second, or watts (W) (kW) Electric power can be calculated by multiplying voltage by current. FORMULA (Electric power) P = power (W); I = current (A); V = voltage (V) P = I · V

Chapter 20 Correct wiring, fuses, circuit breakers, insulation, and grounded plugs help make electrical energy safe to use. *Grounding- transfer of excess charge through a conductor to Earth is called grounding