Electromagnetism

Electromagnetism

Concepts & Calculations

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EDUCATION

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EDUCATION

Start Thinking!

Directions:
• Watch the video.
•Answer the questions that follow.

Multiple Choice

Magnetic force is carried between objects by _____________________ like electrostatic force

• electric fields
• electrons

• photons

• gravitational fields

Match

Match the following

• _______________ is an electromagnet created by the churning of the molten iron core.

• The ___ protects us from solar wind.

• An ____ is a coil of wire that generates a magnetic field when a current is passed through.

Earth

Magnetosphere

Electromagnet

• Earth

• Magnetosphere

• Electromagnet

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EDUCATION

Electromagnetic Force

• The electromagnetic force involves two forms of forces:

o Electrostatic force – the interactions between charged particles; like

charges repel and opposites attract

o Magnetic force – the interactions between magnetic poles; like poles

repel and opposites attract

• One of Physics’ 4 Fundamental Forces:

o Strong Force
o Weak Force
o Electromagnetic Force
o Gravitational Force

• Moving charge creates a magnetic field.
• A moving magnet generates charge.
• Two components of the same force.

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EDUCATION

Electromagnets

• Electromagnet – a type of magnet in which a magnetic field

is produced by the movement of electric charge (current).

• Includes a battery or an electromotive force – the

transfer of electrochemical energy to electrical energy
and “pushes” electric charge through a circuit;
measured in volts

• Copper wire wrapped around an iron core

• How do electromagnets work?

• Current through the wire – moving charges – produce a

magnetic field

• Every coil of wire increases the strength of the magnetic

field; magnetic flux density

• Where are electromagnets used?

• Motors
• Generators
• Transformers

Multiple Choice

If the number of coils increase, the magnetic field strength should _____.

• increase

• decrease

• stay the same

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EDUCATION

Electromagnetic Induction

• Electromagnetic induction – the ability of a magnetic

field to create electric current inside a conductor.

• Magnetic flux – how a material is affected by a magnetic

field; the product of the strength of the magnetic field and
the surface area perpendicular to the magnetic field.

• Magnetic flux can be increased by

oIncrease the strength of the magnet

oRotating or angling the conductor within the magnetic field

oIncreasing the number of loops around the magnetic field

• To produce current, there must be changes of the

magnet’s position over time; must be in motion

• Changing a magnet’s position changes the position of the

magnetic field lines which generates electric current.
o Real world example = generators

https://bit.ly/3OQRv9P

*Watch the

video to learn

more!

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EDUCATION

Electric Motors
• An electric motor is a device that converts

electric energy into mechanical energy.

• Types of motors:

oDC Motors – direct current (current that flows in one direction) motors are powered by batteries

oAC Motors – alternating current (current that constantly changes direction) motors use electromagnets

• Electric motors work by rotating current

carrying wire within a magnetic field.

• The motor’s strength can be increased by:

oincreasing the current flowing through the
wire.

oincrease the strength of the magnet.

oincrease the number of loops in the coil.

Match

The motor's strength can be increased by:

• increasing the __________________ flowing through the wire

• increase the ________ of the magnet.

• increase the _________ of loops in the coil.

current

strength

number

• current

• strength

• number

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EDUCATION

Generators

• A generator is a device that converts

mechanical energy into electrical energy.

• Mechanical energy is provided by rotating

turbines powered by:

o high-pressure steam
o wind
o falling water

• The size of induced current can be

increased by:
o increasing the speed at which the coils

rotate.

o increase the strength of the magnetic

field.

o increase the number of loops in the coil.
o increase the total area of the coil.

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EDUCATION

Magnetism

• A magnetic field is an area of influence around a moving charge. The size of the

field is related to the amount of magnetic force experienced by the charge; the
charge must be in motion to be influenced by the magnetic field.

• The size or magnitude of magnetic force can be determined using terms of

current, I, flowing through a length of wire, L.

• Unlike gravitational or electric force, magnetic force is perpendicular to the

plane formed by the field and moving charge; greatest when perpendicular

Calculations Review:

Math Response

A bee flies perpendicular to the Earth’s magnetic field of 2.46 x 10-5 T. While flying, the bee accumulates 1.0 x 10-12 C. How fast is the bee flying if the magnetic force acting on it is 2.21 x 10-16 N?

______m/s

Type answer here

Correct Answer: 9.0

Deg^°

Rad

Math Response

The magnitude of Earth’s magnetic field in Tampa, Florida is 2.46 x 10-5 T.  If a 2.5 m long wire is carrying a current of 15 A in a direction perpendicular to the field, what is the magnitude of the magnetic force experienced by the wire?

________N

Type answer here

Correct Answer: 0.0009225

Deg^°

Rad