Unit Review By Mrs. Dennison

What is electricity? Electricity is a type of energy caused by small, negatively charged particles called ELECTRONS (after the Greek ‘elecktra’). There are 2 types: STATIC and CURRENT.

Early scientists most likely saw a discharge of electricity while observing a lightning storm.

Lightning is actually static electricity because it is just the atmosphere removing the build-up of electrical charges.

Lightning, as Ben Franklin proved in his famous kite and metal key experiment, is electrical current.

Ever rubbed a balloon on your hair, or shocked yourself after walking across the carpet in wool socks? This is also static electricity.

A student did an experiment with a comb A student did an experiment with a comb. She rubbed it with a wool cloth to charge it up first, then held it over torn up bits of paper. The comb can lift the paper because the paper is now attracted to it.

We also know that electrical current can travel on a path called a circuit. The circuit must be closed to allow the electrons to flow.

When a circuit is open, the electrons cannot flow.

When you leave a room and flip the switch to turn off the light, you are actually opening the circuit. Electrons cannot flow.

Some materials conduct (allow electrical current to flow through them) better than others. Most conductors are made of metal.

The best conductor of electricity that is most often used in electrical wiring is made from copper.

Copper wire is often wrapped in plastic Copper wire is often wrapped in plastic. Plastic material is a good insulator. Other insulators would be wood, glass, paper, cloth, bricks…anything that does not allow electrical current to pass through it.

A metal paperclip would be a conductor. An eraser would be an insulator.

There are two types of circuits: series and parallel There are two types of circuits: series and parallel. Both can be opened and closed.

In a series circuit, there is just ONE PATH on which electrical current can flow. The problem with this circuit is that if one appliance or bulb goes out, they ALL go out.

In a parallel circuit, there is MORE than one path on which electrical current can flow. If one bulb burns out, the rest stay lit because they are on a separate, closed circuit.

Thomas Edison was a prolific inventor Thomas Edison was a prolific inventor. He invented a better lightbulb with a filament that could last longer than any bulb before it.

This is what’s inside an Edison bulb This is what’s inside an Edison bulb. It took many trials and fails to find just the right metal (tungsten) for the filament that wouldn’t burn up right away.

Magnetism is an invisible force. Magnets are attracted to most metals Magnetism is an invisible force. Magnets are attracted to most metals. They have north and south poles, no matter their shapes or sizes.

Like poles, such as a south pole of one magnet, would REPEL, or push away, another magnet’s south pole. Opposite poles, such as a north and a south, would ATTRACT, and pull toward one another.

Many refrigerators have metallic surfaces that are also magnetic Many refrigerators have metallic surfaces that are also magnetic. They make great places to hang magnets and create displays.

Magnets can be fun to just play with, but can also be useful in many ways: computers, cell phones, electromagnets, compasses, etc.

You can actually see a magnetic field if you experiment with iron filings and a magnet!

Michael Faraday showed how electric current in a wire produces a magnetic field.

Michael Faraday created an electromagnet.

Michael Faraday used what he’d learned about electromagnetism to invent the first electric motor. Michael Faraday's electric magnetic rotation apparatus (motor) The first surviving Faraday apparatus, dating from 1822, which demonstrates his work in magnetic rotation. Faraday used this mercury bath to transform electrical energy into mechanical energy, creating the first electric motor.

Electrical motors are examples of mechanical energy that transformed from electrical energy.

There are many forms of energy.

Energy Can Transform!

A family wants to heat their home using electricity A family wants to heat their home using electricity. The electricity can be transformed into thermal energy.

Make sure to study!

Mrs. Dennison feels the cool breeze of a fan Mrs. Dennison feels the cool breeze of a fan. This is an example of electrical energy transforming into mechanical energy.

This toaster will use electrical energy, connected to a heater, that transforms into thermal energy to toast bread.