Magnetism Notes

____________ field lines spread out from one pole, curve around the magnet, and return to the other pole.

o Where are magnetic field lines the strongest? When the magnetic fields of _______ or more magnets overlap, the result is a __________ field.

The nucleus contains ________________ and ________________. Negatively charged electrons move randomly throughout an atom.

What happens to atoms in the magnetic domain in a magnetized material?

If you break a magnet in ½ what happens?

Earth has magnetic fields surrounding two magnetic poles. The location of Earth’s magnetic poles __________ stay the same. __________ winds cause earth’s magnetic field to __________ out on the side of the Earth NOT facing the sun.

Electricity Notes

Charges that are the __________ repel each other. Charges that are ____________ attract each other.

An electric field is a region around a charged object where the object’s electric force is exerted on other charged objects.

Transferring Charge

1. Friction:

2. Conduction:

3. Induction:

Electric current is a _____________ flow of electric charges through a material. A electric _________ is a complete path throughWhich electric charges can flow.

Two different types of circuits

A:_________________________ B:__________________________

Resistance: Two factors that affect the resistance of water flowing in a pipe are ____________ and length. The diameter and length of a wire also affect resistance in a circuit.

KNOW: AN ELECTRIC CURRENT WILL ALWAYS TRAVEL THE PATH OF LEAST RESISTANCE!!!!!!!!

Calculating Resistance: Ohms Law : V=IR

DEFINTION VARIABLE UNITSCurrent The rate at which a

charge passes through a given point

I Amperes (amps)A

Voltage The difference in energy per unit charge as a

charge moves between two points in the path

of a current

V Volts

V

Resistance The opposition to the flow of electric charge.

R Ohms

1. Use Ohm’s law to calculate the voltage of a circuit with a resistance of 15.2 ohms and a current of 0.10 amps.

2. The brake light on an automobile is connected to a 12-volt battery. If the resulting current is 0.40 amps, what is the resistance of the brake light?

3. In a circuit, there is a 0.5-A current in the bulb. The voltage across the bulb is 4.0 V. What is the bulb’s resistance?

IR V

X 1 2 3 4 5 6 7 8 Y

X 1 2 3 4 5 6 7 8 Y

Rectangle B

Rectangle A

Electric Power :The rate at which energy is transformed from one form to another is known as power. The SI unit for power is __________. Power= Voltage(V) X Current(A)

1. A household light bulb has about 0.5 amps of current in it. Since the standard household voltage is 120 volts, what is the power rating for this bulb?

2. A flashlight bulb uses two 1.5-V batteries in series to create a current of 0.5 A. What is the power rating of the bulb?

3. A hair dryer has a power rating of 1,200 W and uses a standard voltage of 120 V. What is the current through the hair dryer?

Electrical Energy (E=Pt)

Electromagnetism Notes

An electric current produces a magnetic field!!!!!!!!!!!!! The magnetic field produced by a ___________ has three distinct characteristics.

o The ___________ can be turned on or offo Its ________________ can be reversed

Reversing the direction of the current reverses the direction of the magnetic field!

o Its strength can be changed Looping the wire increases the strength of the magnetic field!

What is a solenoid?

How does a doorbell ring?

Electromagnets can be used to lift heavy objects. How does this work?

When a wire with current is placed in a magnetic field, _________________energy is transformed into _________________ energy.

An electric current is used to turn the pointer of a galvanometer.o A galvanometer is a device that measures small currents.

An electric motor transforms electrical energy into mechanical energy.

An electric current is induced in a conductor when the conductor moves through a magnetic field.

If a ____________ moves through a coil of a wire, a ______________ is induced in the wire.

A current can be induced two ways

1. Move a conductor through a magnetic field

2. Move a magnet through a coil of wire.

A induced current may flow in only ONE direction. This is called a ______________ current!

o batteries A induced current may reverse directions quickly over and over again. This is called a

_________________ current! o Electric current from a generating plant transmitted at high voltages

Generators use motion in a magnetic field to produce an electric current. In most generators, a source of __________________ energy turns huge turbines. The turbine is attached to the armature of a generator, which produces current.

A MOTOR AND A GENERATOR ARE EXACT OPPOSITES OF ONE ANOTHERA electric motor is an electrical machine that converts electrical energy into mechanical energy! A electric generator is a electrical machine that converts

mechanical energy into electrical energy!

A transformer is a device that _____________ or ______________ voltage. It has two sets of coils called primary and _____________________ coils. Voltage can be changed depending on the number of _________ in each set of coils.

1. Step up transformer Increases voltage ________________________ coil has MORE loops than the ________________ coil

2. Step down transformer Decreases voltage ___________________ coil has MORE loops than the ____________________ coil .