Factors that affect the Magnetic field of an Electromagnet

1. The core material The denser the material the

stronger the field2. The current intensity

Higher the current stronger the magnetic field

3. Number of loops (number of turns)

More turns gives a stronger field.

Cores

A Core is the object that is inserted into the solenoid, creating an electromagnet.

Different metals can be used for the core: iron, steel, nickel or cobalt.

Iron is most commonly used because when you turn off the electricity it demagnetizes.

Metals like steel remain magnetized thus creating a permanent magnet.

Do not want a

permanent magnet for the core

Core Material

Ferromagnetic cores strengthen the magnetic field Iron, steel, nickel & cobalt Iron is a VERY GOOD core

Wood, plastic and Aluminum are not very good products for a core

Number of Loops

As the number of loops increases, the strength increases

Few loops Many loops

Current Intensity

As the current intensity increases, the strength increases

I = 5 amps I = 10 amps

Which has a stronger magnetic field?A B

Iron Wood

1 - Number of loops is the same2 – Intensity is the same3 – But the core is different

I = 5 amps I = 5 amps

Result:(A) Iron is better because it is a ferromagnetic core

Which has a Stronger Magnetic Field

A B Iron Iron

# of loops are different Intensity is the same Core is the same

I = 2 amps I = 2 amps

3 loops 5 loops

Result:B is stronger: more magnetic loops = a stronger magnetic field

Which has a Stronger Magnetic Field

A B Iron Iron

# of loops is the same Intensity is different Core is the same

I = 2 amps I = 10 amps

5 loops 5 loops

Result:B is stronger because current intensity is greater

Which has a Stronger Magnetic Field

A B Nickel Nickel

Whenever the loops & the current intensity are different but the cores are the same, use the following equation

I = 5 amps I = 2 amps

3 loops 5 loops

Strength of field = current intensity x (# of turns)A 15 = 5 amps x 3 turnsB 10 = 2 amps x 5 turns

A therefore has a stronger magnetic field

Mathematical Relationship

To find the strength of the electromagnet scientists use the following equation: F = IN F is force or strength of the

electromagnet I is the current intensity traveling

through the wire N is the number of loops around the

coreRemember

Which Electromagnet has the Strongest Magnetic Field

Current = 10ATurns = 6

Current = 7ATurns = 10

60 = 10A x 6 turns 70 = 7A x 10 turns

Strongest

Factors affecting magnetic field: Core material,

Iron is always the best core material

Number of turns The more loops the stronger the field

Current Intensity High current results in stronger intensity

Origins of Magnetism of Matter

Scientists believe that magnetism comes from spinning electrons around the nucleus of the atom.

When atoms clump together they form a domain.

Similar electron spins produce a strong domain, where as opposite electron spins cancel one another out and produce a weak domain.

If enough domains align in the same direction, this will create a magnetic field.

Origins of Magnetism of Matter

How to Magnetize an Object

Bring the ferromagnetic substance in contact with another magnet.

Bang the ferromagnetic substance (example: striking a nail repeatedly).

Heat up the substance and cause the domains to align.

Run electric current through the ferromagnetic substance.

Please note that all of these methods can also de-magnetize a magnet.