Electromagnetic Forces

Lesson 11.4: Electromagnetic Force

If you look at the back of a plastic personal card, you will notice a black stripe on it. This stripe is made of magnetic particles that are arranged in a manner that holds information. When the card is put through a reader, the information is read by the reader and sends the information to a computer for verification. Because the particles are magnetic, they can be rearranged with a magnet which destroys the information on the card.

Multiple Choice

A compass behaves as it does because the moon acts as a giant magnet

• True

• False

Multiple Choice

A maglev train floats above its rails due to

• Magnetism

• Electric Charge

• Polarity

• Static Discharge

Multiple Choice

A magnetic pole is part of a magnet where the magnetic effect is weakest.

• True

• False

Drag and Drop

The law of ​

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of charge states that charges are not created or destroyed.

Drag these tiles and drop them in the correct blank above

conservation

magnetism

repulsion

Voltage

Static

Multiple Choice

Magnets attract iron.

• True

• False

Lesson Objectives

• Explain how electric current is related to magnetism

• Identify some characteristics of a magnetic field produced by a current

• Describe the characteristics of solenoids and electromagnets

How are Electric Currents & Magnetic Fields Related?

• Magnets and Electricity share several elements

  • Both create fields around an object

  • Both follow similar rules

    • Opposites attract, Same Repel

• From the similarities, it is possible to show a relationship between the two

Oersted's Experiment

• Danish Scientist Hans Christian Oersted accidentally discovered that an electric current can produce a magnetic field

  • Set up a current for a demonstration and noticed that his compass changed directions when brought near the current

Oersted's Experiment

• Repeated his experiment several times

  • whenever a current flowed through the wire, it changed the Compass Needles's Direction

  • When the Current was removed, the compass returned to normal

Electric Current & Magnetism

• Oersted's Experiment showed that an electric current produces a magnetic field

• Electromagnetism: The relationship between electricity and magnetism

Drag and Drop

​

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discovered that whenever there is electricity, there is magnetism.

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Oersted

Newton

Gallileo

Ferris

Multiple Choice

An Electric ___________ produces a magnetic field.

• Charge

• Discharge

• Current

• Spark

What is the Magnetic Field Produced by a Current Like?

• The Magnetic Field produced by a current has strength and direction

• The Current can be turned on or off and change the magnetic field

  • When a field is turned on or off, the strength changes and the direction reverses

Changing the Strength of a magnetic field

• There are two ways a person can change the strength of a magnetic field

  • Increase the amount of current in the wire

  • Add Loops to the wire

    • When the wire is looped, the magnetic field lines a brought closer together and made stronger

      • Every additional loop strengthens the magnetic field

Currents that Generate Electromagnetic Fields

• There are two types of currents that can generate an electromagnetic field

  • Solenoids

  • Electromagnets

Solenoids

• Solenoid: A Coil of Wire with a current

  • The two ends act like the poles of a magnet

    • Poles can change if the direction of the current changes

Electromagnets

• Electromagnet: A solenoid with a strong magnetic material on the inside

  • Both the current of the wire and the magnetized core produce magnetic fields, making the magnetic attraction much stronger

  • Can be turned on and off with the current

• Electromagnets are used in many different objects

  • From small electronics to large industrial tools

Increasing the Strength of Electromagnets

• There are four ways to increase the strength of an Electromagnet

  • Increase the Current in the Solenoid

  • Add more Loops to the Wire

  • Wind the Coils of the Solenoid closer together

  • Use a material that is more magnetic in the core

Drag and Drop

A(n) ​

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is a coil of wire that has a current running through it.

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solenoid

electromagnet

Oersted

Oersted

Oersted Magnet

magnet

generator

Multiple Choice

How can you increase the strength of an electromagnet?

• Moving a compass close to the electromagnet

• Adjusting the magnetic declination

• Using a stronger magnetic material for the core

• Reversing the magnetic Domains

Drag and Drop

You can increase the strength of a magnetic field by ​

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the amount of ​

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in the wire

Drag these tiles and drop them in the correct blank above

Increasing

Loops

Decreasing

Charges

Iron

Neutralizing

Multiple Choice

Both solenoids and electromagnets produce magnetic fields using

• electric currents and coiled wires

• compasses and magnetic fields

• coiled wires and a ferromagnetic core

• electric current and a battery

Multiple Select

A magnetic field produced by a current has what two things?

• Strength

• Direction

• Charge

• Static

Multiple Choice

What is being represented in the picture?

• An Electromagnet

• Static Discharge

• A Solenoid

• A Compass