Electricity & Magnetism Chapters 6,7,8,9 & 10 Electricity & Magnetism

Electrons are free-moving (can be lost or gained) The Atom 3 Subatomic Particles 1. Proton: (+), nucleus 2. Neutron: neutral, nucleus 3. Electron: (-), outside Electrons are free-moving (can be lost or gained)

Force of Repulsion: Like charges repel each other Electrical Forces Force of Repulsion: Like charges repel each other Force of Attraction: Opposite charges attract each other

Region around a charged particle where the force is noticeable Electrical Field Region around a charged particle where the force is noticeable Strongest near the charged particle.

Energy created by electrons moving from one place to another. Electricity Energy created by electrons moving from one place to another. Static Electricity: build up of electrons Ex) Lightning Click hear for more information

1. Friction: rubbing objects together to separate charges. Methods of Charging Objects 1. Friction: rubbing objects together to separate charges. Ex) rubbing feet on carpet, a car seat, balloon, etc...

2. Conduction: transfer of electrons through direct contact. Conductors: easy flow of electrons Insulators: inhibit flow of electrons

Ex) sticking a balloon to wall 3. Induction: rearrangement of electrons by indirect contact. Ex) sticking a balloon to wall

Electroscope Detects electrical charges; leaves spread apart in the presence of charges

Voltage: The “push” that makes electrons move. Flow of Electricity Voltage: The “push” that makes electrons move. Unit: volt Symbol: “V” Current: the flow of electrons through a wire Unit: ampere or amp Symbol: “I”

Resistance: opposition to the flow of electricity. Unit: ohm Symbol: “R” 1. Type of Material: good conductors = less resistance 2. Thickness of Wire: large wire = less resistance

Ohm's Law Current (amp) Voltage (volt) I = V R Resistance (ohm)

Wet Cell: Uses liquid (cars). Dry Cell: Uses a jelly-like fluid. Batteries Wet Cell: Uses liquid (cars). Dry Cell: Uses a jelly-like fluid.

Current Direction 1. Direct current: electron flow is always in the same direction (batteries) 2. Alternating current: electrons reverse the direction of flow 60 times per second (homes)

Electrical Circuits Parts of a Circuit:

Series Circuit One path for the electrons to take; if one part goes out, the circuit is open electricity will NOT flow.

Parallel Circuit More than one path for the electrons; if a break occurs in one branch, the electrons can still flow.

The amount of energy an appliance uses depends on: Electrical Energy The amount of energy an appliance uses depends on: 1. Total power used 2. Total time

A force of attraction or repulsion due to an arrangement of electrons. Magnetism A force of attraction or repulsion due to an arrangement of electrons. Forces are strongest at the poles North and South Poles Click hear for more information

Attraction vs. Repulsion Opposites attract Likes repel

1. Natural Magnet: occur naturally Magnetic Materials 1. Natural Magnet: occur naturally 2. Magnetic Induction: creating temporary magnets 3. Temporary: soft iron is easy to magnetize but loses it quickly.

4. Permanent: cobalt & nickel are harder to magnetize but stay permanently.

Earth is surrounded by a magnetic field. Earth as a Magnet Earth is surrounded by a magnetic field. Magnetic Variation: compasses point to magnetic north, not geographical north. (smallest at equator)

Magnetic Domains In magnetized objects, all the north and south poles point in the same direction.

There are 3 ways to disturb the domains... Disturbing the Domains There are 3 ways to disturb the domains... 1. Heat up 2. Drop repeatedly 3. Hit hard

Uses electricity and magnets Electromagnets Uses electricity and magnets Wrap wire around a soft iron core and pass electricity through the wire. Increase strength by: 1. Increase # of loops 2. Increase current flow

1. Motors: converts electrical energy into mechanical energy. Electric Devices 1. Motors: converts electrical energy into mechanical energy. 2. Generators: converts mechanical energy into electrical.

Step-up: increases voltage Step-down: decreases voltage 3. Transformers: increase or decrease the voltage of an alternating current. Step-up: increases voltage Step-down: decreases voltage

4. Circuit Breaker: protects your household circuits from overloading. Fuse: a piece of metal that melts when overloaded