Magnetism and Electricity: What are the properties of magnetism and electricity?


Magnets

We use magnets every day. Examples include: car doors, door hinges, computers, vacuum cleaners, blenders, CD players, washing machines, fax machines, escalators, elevators, loud speakers, credit cards, televisions, fridge doors, toys, electric toothbrushes, junk yards, and roller coasters.

What kinds of materials attract magnets?

We begin learning about magnets through exploring objects that stick and do not stick to a magnet. Objects with iron, nickel, or cobalt content attract magnets. The most common of these metals is iron. Steel is also derived from iron.

Magnets can also stick to each other. When magnets stick to each other, there is a force of attraction. When magnets push apart from each other, it is a force of repulsion. Magnets have South and North Poles. Opposite poles attract.

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Investigating More Magnetic Properties

The area around a magnet is called a magnetic field.

The magnetic force can also go through most materials (like cardboard or wood).

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When a magnet touches an object that contains iron, that iron becomes a temporary magnet, as long as it is in the magnetic field of the permanent magnet. Temporary magnetism is called induced magnetism.

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Can we measure the force of attraction between magnets?

We can measure the force of attraction between magnets using a balance, two magnets, spacers to create distance, and washers to measure the force of attraction.

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The greater the space between magnets, the lower is the force of attraction between them.

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Vocabulary

A force is a push or pull.

A magnet is an object that sticks to iron.

Magnetism is a kind of force.

When magnets pull together, they attract each other.

When magnets push apart, they repel each other.

The Earth's magnetic field is like a giant magnet with a South and North Pole.

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In lighting a bulb and running a motor, we build simple circuits and learn that a D-cell (battery) is a source of electric energy, and the bulb or motor in this case is an energy receiver. A circuit is a pathway through which electric current flows.

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A circuit needs to be closed in order for the electricity to flow. Below is a simple series circuit.

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When the circuit is open, electricity does not flow. To open the circuit, just open the switch, so that metal is no longer touching metal.

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Objects that conduct electricity are called conductors. All metals are conductors. Objects that do not conduct electricity are called insulators, which are nonmetallic. For example, the copper wire allows the flow of electricity, and is therefore an insulator. The rubber around the wire blocks the flow of electricity, and is therefore an insulator.

Conductors (Metallic)

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Insulators (Nonmetallic)

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Electricians and electrical engineers draw circuits as schematic diagrams. The wires are drawn like a square, the D-cell (battery) and the light bulb also have their own symbols (see below).

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A series circuit (see below) has two or more components(parts) attached to a source so that the current flows through one path through all the components. If one component is disconnected, the current stops flowing to the rest of the circuit. Because they are sharing the current, the bulbs are less bright. In a series circuit, if even one of the light bulbs in an older-style string of Christmas tree lights burns out or is removed, the entire string stops working until the bulb is replaced.

A parallel circuit has two or more components, each with an equal pathway to the source. This means that they are not sharing the electric flow. Both bulbs stay bright.

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In a series circuit, two D-cells facing the same direction make the light brighter. However, if the D-cells face opposite directions, the electricity would not flow.

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In a parallel circuit, the D-cells could be positioned parallel to each other.

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Energy from solar panels could power the circuit similarly to a battery.

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Electromagnets are objects containing iron that can become temporary magnets (through induced magnetism) when an electric current flows through them. We can create electromagnets by winding an insulated wire around the piece of iron. The greater the number of winds, the stronger the magnetic force.

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  • Tighter coils produce a stronger electromagnet.

  • All the coils need to be wound in the same direction.

  • A D-cell added in series makes a stronger electromagnet, but, added in parallel, does not strengthen the electromagnet.

  • Thicker wires make a stronger electromagnet.

Electromagnets are used in car engines, in doorbells, and in junkyard cranes. See images below.

Doorbell

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Vocabulary

The D-cell is the source of electricity.

A battery refers to more than one cell, but most people use the words battery and D-cell interchangeably.

An electricity source provides the energy to light the bulb.

An electricity receiver is a component that uses the electricity from the source to make something happen.

A circuit is a pathway for the flow of electricity.

The filament of a bulb is the part that gets hot and produces light.

D-cells, bulbs, and wires are circuit components.

A circuit base holds many components needed to build a circuit.

A Fahnstock clip is a metal clip that connects wires in a circuit.

A switch is a device used to open and close circuits.

An open circuit is an incomplete circuit through which electricity will not flow.

A closed circuit is a complete circuit through which electricity flows.

A schematic diagram is a way to represent a circuit on a piece of paper.

A conductor is a substance, commonly a metal such as copper or aluminum, through which electricity will flow.

An insulator is a material that prevents the flow of electricity, commonly plastic, rubber, glass, or air.

Resources

1. Video: Earth's Magnetic Field

2. Video: The Northern Lights

3. Link to articles, games, and quizzes and magnetism and electricity

3. Article: What is Magnetism?

4. Video: Why do magnets attract iron?

5. Magnetism and Electricity Unit Summary

6. Video: Designing Door Alarms

7. Video: Electromagnetism

8. Presentation: How Solar Storms Work

9. Magnetism and Electricity Glossary

10. Video: Bill Nye the Science Guy on Magnetism
11. Video: Bill Nye the Science Guy on Electricity
12. Video: MIT Lecture on Magnetism and Electricity
13. Video: Magnets
14. Video: Model Maglev Train
15. Instructions on making a maglev train
16. Documentary on Biomagnetism
17. Video: How to Make an Electric Motor
18. Video: How animals navigate
19. Video: Magnetism and Electromagnetism: The Power of Attraction
20. Videoclip: Electromagnet example
21. Video: Maglev Train