Unit 8 Part 3-Electromagnetic Force

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Section 3: 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

An object becomes charged when the atoms in the object gain or lose

• electrons
• protons
• neutrons
• Iron

Multiple Choice

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

• True

• False

Multiple Choice

If you rub a glass rod with a piece of silk, the rod becomes positively charged. This means that

• friction destroyed electrons in the rod.
• the silk has become negatively charged.
• protons have moved to the rod.
• glass attracts more protons.

Multiple Choice

A maglev train floats above its rails due to

• Magnetism

• Electric Charge

• Polarity

• Static Discharge

Multiple Choice

If you bring a charged object near an electrically neutral surface without allowing the object to touch the surface, the charges in the surface are rearranged by...

• friction.
• convection.
• induction.
• conduction.

Multiple Choice

Magnets attract iron.

• True

• False

Multiple Choice

What causes static electricity?

• only an object losing electrons
• only an object gaining electrons
• when positive and negative charges balance
• when positive and negative charges are not balanced

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

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.

Drag these tiles and drop them in the correct blank above

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

Multiple Choice

Electromagnetism is the interaction between _____ and _____.

• Magnets and Light Bulbs

• Open circuits and Closed circuits

• Potential energy and Kinetic energy

• Electric charges and Magnets

Drag and Drop

A(n) ​

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

Drag these tiles and drop them in the correct blank above

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 ​

Placeholder

the amount of ​

Placeholder

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

Multiple Choice

The closer to the wire coils in an electromagnet, the _____ the magnetic field.

• More flexible

• Stronger

• Weaker

• Louder

Open Ended

Suppose you were lost and trying to get home with only a compass. You have two options of sidewalk to travel on: the sidewalk closer to the river or the one closer to the with power lines. Which sidewalk would be easier to find your direction on. Explain why.