Factors that affect the Magnetic field of
an Electromagnet
1.
The core material

2.
The current intensity

3.
The denser the material the
stronger the field
Higher the current stronger
the magnetic field
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
I = 5 amps
I = 5 amps
1 - Number of loops is the same
2 – Intensity is the same
3 – But the core is different
Result:
(A) Iron is better because it is a ferromagnetic core
Which has a Stronger Magnetic Field
A
B
Iron
Iron
I = 2 amps
3 loops



I = 2 amps
5 loops
# of loops are different
Intensity is the same
Core is the same
Result:
B is stronger: more magnetic loops = a stronger magnetic field
Which has a Stronger Magnetic Field
A
B
Iron
Iron
I = 2 amps
5 loops



I = 10 amps
5 loops
# of loops is the same
Intensity is different
Core is the same
Result:
B is stronger because current intensity is greater
Which has a Stronger Magnetic Field
A
B
Nickel
Nickel
I = 2 amps
I = 5 amps
3 loops
5 loops
Whenever the loops & the current intensity are different but
the cores are the same, use the following equation
Strength of field = current intensity x (# of turns)
A 15
=
5 amps
x
3 turns
B 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



Remember
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
core
Which Electromagnet has the Strongest
Magnetic Field
Current = 10A
Turns = 6
60 = 10A x 6 turns
Current = 7A
Turns = 10
70 = 7A x 10 turns
Strongest
Factors affecting magnetic field:

Core material,


Number of turns


Iron is always the best core material
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.
Origins of Magnetism of Matter


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.
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.