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Electricity

- Chapter 1

Electric Charge

- Charges Exert Force
- Atoms are composed of particles with ______.

The law of electric charges states that like

charges _____and opposite charges _______

The Force Between Protons and Electrons

- Protons and electrons have ________ charges, they

are ________ to each other

The Electric Force and the Electric Field

- _____________ the force of attraction or

repulsion on a charged particle that is due to an

electric field - ____________ the space around a charged object

in which another charged object experiences an

electric force

Charge it!

- Friction

- Conduction

- ________- occurs when electrons are wiped
- from one object to another

- __________ electrons move from one object to

another by direct contact.

Charge it!

- _________ charges in an uncharged metal object

are rearranged without direct contact with a

charged object

Conservation of Charge

- When you charge something by any method,

____________________________________. The numbers

of ________ and _______ stay the same. - Detecting Charge
- You can use a device called an _____________ to

see if something is charged

Moving Charges

- __________- a material in which charges can move

easily - Examples
- __________- a material in which charges
- cannot move freely
- Examples

Static Electricity

- _________________ electric charge at rest

produced from friction or induction - _________________ the release of electricity

stored in a source

1.2 Electric Current Energy

- _______________ rate at which charges pass a

given point - When you flip a switch, an _____________ is set

up in the wire at the speed of light. The

electric field causes the _________ in the wire

to move. - This electric field is created so quickly that

all electrons start moving through the wire

_________. - Think of the electric field as a command to the

electrons to charge ahead.

Types Electric current

- Direct Current (DC)

- Alternating Current (Ac)

- ___________________ charges always flow in one

direction. - Ex

- ___________________ charges shift
- from flowing in one direction to

flowing in - the reverse direction
- EX

Voltage and Energy

- _______ the potential difference between points
- SI unit
- You can think of voltage as the amount of energy

released as a charge moves between two points in

the path of a current. - As long as there is a voltage between _________,

charges will flow in the wire. The ____ of the

current depends on the _______

Varying Nature of Voltage

- Different devices need different levels of

voltage. - 1.5 V 9 V

12 V

Resistance

- ___________ opposition to the flow of electric

charge - SI unit
- Good conductors, such as copper, have

_____________ - Poor conductors, such as iron, have

______________ - Resistance depends on thickness, length,

temperature - Thick, _____ wires have ____ resistance than

____, thin wires. - The resistance of metals _________ as temperature

_________

Resistance

Generating Electrical Energy

- Remember energy is not created or destroyed it

only changes forms - Parts of a Cell
- A cell contains a mixture of chemicals called an

__________. Every cell also has a pair of

__________made from conducting materials

Types of Cells

- There are 2 types of cells
- ___ have an electrolyte
- Example batteries sulfuric acid is the

electrolyte - ___ have a dry electrolyte
- Example small radios or flashlights

Generating Electrical Energy

- Cells change chemical or radiant energy into

electrical energy. Batteries are made of one or

more cells. - ____________ can take thermal energy and transfer

it to electrical energy. - _________convert light energy into electrical

energy.

1.3 Electrical Calculations

- How fast is a nanosecond? A nanosecond (ns) is

one-billionth of a second. Electrical signals

travel at 30 cm/ns. Calculate how far electrical

signals travel in 1 second.

Connecting Current, Voltage, and Resistance

- Georg Ohm Ohm (1789 1854) studied the resistance

of materials. He measured the current that

resulted from different voltages applied to a

piece of metal wire. - Ohms Law the ratio or voltage (V) to current

(I) is the resistance (R) of a material - V I x R

Electric Power

Unit SI Unit

Voltage (V) V - volt

Current (I) A- Amps

Resistance (R) Ohm - ?

Ohms Law Calculations

- Ex 1 What is the voltage if the current is 2 A

and the resistance is 12 ? ? - Ex 2 Find the voltage if the current is 0.2 A

and the resistance is 2 ?

Ohms Law Calculations

- Ex 3 The resistance of an object is 4 ?. If the

current in the object is 9 A, what is the voltage

used? - Ex 4 An object has a resistance of 20 ?.

Calculate the voltage needed to produce a current

of 0.5 A.

Electric Power

- Electrical Power (P) the rate at which

electrical energy is converted into other forms

of energy - Si Unit Watts (W)
- Power voltage x current
- P V x I

Unit SI Unit

Voltage (V) V - volt

Current (I) A- Amps

Power (P) W - Watts

Electrical Power Calculations

- Ex 1 A toaster draws approximately 10 A of

current. A home receives 120 V at each electrical

outlet. What is the power of the toaster? - Ex 2 A car uses a 12 V battery. One headlight

draws 3.0 A. What is the power of the headlight?

Electrical Power Calculations

- EX 3 A light bulb draws a 0.5 A current at a

voltage of 120 V. What is the power rating of the

light bulb?

Electrical Energy

- Measuring Household Energy Use
- Different amounts of electrical energy are used

each day in a home. Electric companies usually

calculate electrical energy by multiplying the

power in kilowatts by the time in hours.

1.4 Electric Circuit

- Just like a roller coaster, an electric circuit

always forms a loop it _____ and ____ at the

____ place - Parts of an Electric Circuit
- (light bulb, appliance)

Switches

- Sometimes, a circuit also contains a _____
- _____ opens or closes a circuit
- _____ electrons can ____
- _____ electrons _____________

Types of Circuits

- ______________ a circuit in which the parts are

joined one after another such that the current in

each part is the same. - _________for charges to follow charges must

flow through each part of the circuit - The voltage across each load is _________

Series circuits are useful in wiring burglar

alarms. If any part of the circuit fails, there

will be __________in the system and the alarm

will sound.

Types of circuits

- _______________- a circuit in which the parts are

joined in branches so that the voltage (potential

difference) across each part is the same - Loads do ___have the _________________
- Charges have more than ___ path to follow

Parallel Circuits are used in almost all

appliances and decorative string lights

Household circuit safety

- Circuits can ____ if they are __________ or a

wire breaks or has water damage. - To prevent fire
- A thin strip of metal in circuit that the charges

flow through. - If the current is too high, the metal will

melt and the circuit - is broken
- A switch that automatically opens if the current

is too high. A metal strip heats up, bends, and

opens the switch stopping the flow of current