Unit 7- Electricity

Electricity

flow of electrons or charge

Static Electricity

the net accumulation of electric charger of an object

The two types of chargers

\+ and -

the net charge= 0

What happens when you have the equal amount of + and - charge

protons

positive charge

electrons

negative charge

neutrons

neutral (0) charge

negative charge

When a substance has more electrons than protons

positive charge

When a substance has more protons than electrons

attract

opposite charges

repel

like charges

Electric field

an area surrounding an electron that exerts a force on anything nearby with an electric charge

Conductors

allow electrons to move easily through it

Insulators

don't allow electrons to move easily through it

Electroscope

made of two thin metal leaves attached to a metal rod with a knob at the top. Shows charges of induction.

Leyden Jar

device that stores static electricity between two electrodes on the inside and outside of a glass jar

Pontential Difference (voltage)

the difference in potential between two places

Potential Difference

measured in volts

Voltmeter

a device we use to measure voltage

Current

the flow of electrons through a wire or any conductor

Current

measured in amps

Dry cell

an electron pump that has potential difference between the positive and negative terminals

Wet cell

contains two connected plates made of different metals or metallic compounds in an electrolyte solution

Wall sockets

these have a potential difference across the two holes - usually 12 volts

Electric Generator

uses some type of mechanical power to spin a coil of wire in a magnetic field

Mechanical sources

a) Fossil Fuels (produce steam)

b) water (hydroelectric)

c) Wind

d)Nuclear (produce steam)

e) Geothermal

f)Solar

Resistance

the tendency for an object to oppose the flow of electrons.

Changing electrical energy into thermal energy and light

Measured in ohms

Low resistance

excellent conductors (ex. copper wire)

High resistance

thermal energy (ex. stone)

Ohm's law equation

V\=IR

Ohm's Law

One volt across the circuit with a resistance of 1 ohm produces a current of 1 amp. The greater the voltage, the greater the current. But the higher the resistance, the lower the current.

Series circuit

the current only has one path to travel along

Determining resistance in series circuit

Rt\=R1+R2+R3

Parallel circuit

the circuit has a separate branch for the current path to travel along

Determining resistance in a parallel circuit

1/Rt\= 1/R1+1/R2\=1/R3

This type of circuit is used in houses

parallel

fuses, circuit breaker

Devices that can keep a circuit from overheating

Electrical power

the rate at which electrical energy is converted to another form of energy.

Power equation

Power= current x voltage

P=RI

Measured in watts

DC (Direct Current)

Flows only one direction through a wire

ex. dry cell battery

AC (Alternating Current)

Reverses its direction in a regular pattern

ex. wall outlets

Transformers

Increase or decrease the voltage of an alternating current traveling through power lines