Electromagnetism 1: Magnetism

Electromagnetism 1

By Akram Varqid

Revision

You must already know

Electric charges, force, and field

Voltage, Current, Resistance and how they relate and formulas

Electrical Energy and Power

Electric Circuit (Series and Parallel)​

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Object that have magnetic pole

Can pull metallic object

Can pull / repel other magnet​

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Magnet

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Multiple Choice

Which is magnetic material?

• Gold

• Iron

• Plastic

• Wood

Magnetism

Force between pole (south and north)

Same pole will repel and different pole will attract

Stronger magnet have stronger force (stronger attract / repel)

Both pole must exist at the same time​

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Multiple Choice

North and north pole will ...

• Attract

• Repel

• Do nothing

• Do everything

Multiple Choice

North and south pole will ...

• Attract

• Repel

• Do nothing

• Do everything

Multiple Choice

South and north pole will ...

• Attract

• Repel

• Do nothing

• Do everything

Multiple Choice

South and south pole will ...

• Attract

• Repel

• Do nothing

• Do everything

All magnet have two different pole.

Between the pole is there is magnetic field

Magnetic field is region where there is magnetic force​

From north to south​

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Magnetic Field

Stronger magnetic field:

More lines / closer lines

Connecting north and south

Depends on the position and shape of magnet​

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Magnetic Field Drawing

Multiple Choice

Magnetic field is from

• South to north

• North to north

• North to south

• South to south

Multiple Choice

The closer magnetic field line the magnetic force is

• Stronger

• Weaker

Multiple Choice

The more magnetic field line the magnetic force is

• Stronger

• Weaker

Always have magnetic properties

More difficult to adjust magnet strength

Strength depend on physical change​

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Permanent Magnet

Only magnetic when there's current flow

Easy to adjust magnet strength

Strength depend on electrical change​

Electromagnet

Multiple Choice

Which is not always having magnetic properties all the time?

• Permanent magnet

• Electromagnet

• Bar Magnet

Permanent magnet

How to make

Take a magnetic material and rub them together

This will align the domain inside the material

The magnetic field become aligned and stronger

Now it become a magnet

Example: Used screwdriver​

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Permanent Magnet

How to destroy

1. Heating

2. Shock (Drop or hit with hammer)

3. Put inside changing magnetic field (coil with ac)​

This will change the aligned domain to unaligned.

Magnetic field weaker, no longer magnetic

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Multiple Choice

How to destroy a magnet?

• Say hurtful words to it

• Dip it in water

• Put in electric shock

• Throw it to the wall

Electromagnet

How to make and destroy

Take a direct current power supply / battery and connect to a wire

You can also shape the wire into coil.

The more coil, the stronger magnet

The more current / the less resistance, the stronger magnet

Turn off current, no longer magnetic​

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Multiple Choice

Electromagnet that is weaker have

• 5 Coil

• 10 Coil

• 15 Coil

• 2.0 Coil

Multiple Choice

Which electromagnet the strongest

• 5 A

• 15 A

• 3 A

• 2.0 A

Multiple Choice

Electromagnet active when circuit is

• Open

• Closed

In a wire, if the current flowing downward, the magnetic field ​shows direction circling it, with north pointing clockwise and vice versa

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Magnetic field by wire

Wire shaped into solenoid will have north on one end and south on the other

This is because clockwise or counterclockwise go inside coil and outside​

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Magnetic field of solenoid

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Right hand rule is useful to determine the direction of current or magnetic field if you know one of them

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Right hand rule

It can also be used on coil, the thumb will be magnetic field instead

Determine the direction current in and out

Determine wire facing you is up or down

Your fingers follow that direction​

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Right hand rule for coil

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Multiple Choice

If there is current coming out of a table, what will be the magnetic field on the table?

• Clockwise

• Counterclockwise

• North into table

• North out of table

Multiple Choice

• A

• B

• C

• D

Multiple Choice

• A

• B

• C

• D