Electrical Energy & Magnetism Electricity Intro: 22min

Electrical Energy Energy produced by moving electric charges. – Charges can be positive (+) or negative (-), Ions Caused by the gain or loss of electrons from the orbits of an atom. Atoms are made of: – Neutrons, in the nucleus, neutral (0) – Protons, in the nucleus, positive (+) – Electrons, on the orbits, negative (-)

Ions Atoms have equal numbers of protons & electrons, electrically neutral. – Protons are stationary, don’t move. – Electrons are free to move. Loss of e- = positively charged atom – More protons than electrons Gain of e- = negatively charged – Fewer protons than electrons. Gains Outer Electron Positive Ion Negative Ion P=11 e-=11 P=11 e-=11 P=11 e-=10 P=11 e-=12

Electric Forces The difference between the two charges, + and -, causes them to have different forces: 1.Force of attraction – force between oppositely charged particles. (+/-) 2.Force of repulsion – force between particles of the same charge. (+/+ or -/-) Rule of Electric Charge: Like charges repel, opposite charges attract!

Electric Fields A field that extends outward through space from every charged particle. – Field is strongest, closest to the charged particle. – Field is weakest, farther from the charged particle.

Conduction The flow of electrons from one object to another through direct contact. – Conductors permit the flow of electric charges freely. Electrons in the atoms are free to move. – Metals; silver, copper, aluminum, and mercury. – Insulators do not allow electric charges to flow freely. Electrons are tightly bound and cannot move throughout the material. – Rubber, glass, wood, plastic, air, feathers.

ItemLight Bulb Light?Insulator/Conductor Wood Copper Glass Steel No Yes Insulator Conductor

Circuits In order for electricity to flow, electrons need a closed path to travel through – circuit. Parts of a Circuit: – Energy source Battery or Electric Outlet – A load, or resistance Light Bulb – Wires – Switch Opens and closes the flow of electricity through the circuit. Switch Energy Source Wires Load

Types of Circuits 1.Series Circuit – all the parts of the circuit are connected one after another. – Only one path for electrons to travel. From positive to negative – Disadvantage: A break in any part of the circuit stops all flow of electrons. Christmas tree lights +-

Types of Circuits 2.Parallel Circuits – Different parts of an electric circuit are on separate branches. Several paths for electrons to travel. Advantage: A break in path will not take out the entire circuit. – Household Circuits

Lodestone 2000 years ago, Greeks living in Magnesia discovered a rock with an unusual trait, it attracted materials that contain iron. – Named the rock magnetite. When allowed to swing freely, the same end of the rock would always point toward the north star, (leading star or lodestar) – Magnetite is also known as lodestone.

Magnetism An invisible force of attraction or repulsion, of a magnetic material, due to the arrangement of its atoms. – Electrons in their outer orbits are in constant motion and spin causing a magnetic field. When the electrons all point in the same direction, its said to have magnetic domain.

Magnetic Domain Metals = Magnetic Domain – Electrons all point in the same direction Nonmetals = No magnetic Domain – Electrons have random arrangements.

Magnets All magnets have two ends where magnetic effects are strongest – poles. – North and South Have magnetic forces - lines of force extending from one pole of a magnet to the other. – It is the area over which the magnetic force is exerted. Magnetic forces always move from the north pole of a magnet to the south pole. – strongest at the poles.

Magnetic Forces

Just like electric forces, magnetic forces follow the same rule: Opposites attract, like repels. Opposites Attract Like Repels