Electromagnets

Electromagnets

1. ELECTROMAGNETS
Objectives:
2.4Demonstrate the effect of a core on the
behavior of an electromagnet
2.5Explain the properties of magnetized matter
using the simplified atomic model.
2.6Factors that affect the magnetic field of an
electromagnet
2.7Determine the mathematical relationship that
affects the magnetic force of an
electromagnet.

2. Electromagnet
An electromagnet is a type of
magnet in which the magnetic field
is produced by electric current.
A metal core cylinder is inserted in
a solenoid.
A solenoid is a coil of “live” wire.

3. Factors that affect the Magnetic field of
an Electromagnet
1.The core material
2.The current intensity
3.Number of loops
Important

4. Core Material
A Core is the object that is
inserted into the solenoid,
creating an electromagnet
Ferromagnetic cores strengthen
the magnetic field
Iron, steel, nickel & cobalt
Iron is a VERY GOOD core material
Wood, plastic, and aluminum are
not good materials for a core.

5. Which has a stronger magnetic field?
A B
Iron Wood
1 - Number of loops is the same
2 – Intensity is the same
3 – But the core is different
I = 5 amps I = 5 amps
Result:
(A) Iron is better because it is a ferromagnetic core

6. Number of Loops
As the number of loops increases,
the strength increases
Few loops Many loops

7. Which has a Stronger Magnetic Field
A B
Iron Iron
Intensity is the same
Core is the same
# of loops are different
I = 2 amps I = 2 amps
3 loops 5 loops
Result:
B is stronger: more magnetic loops = a stronger magnetic field

8. Current Intensity
As the current intensity increases,
the strength increases
I = 5 amps I = 10 amps

9. Which has a Stronger Magnetic Field
A B
Iron Iron
# of loops is the same
Core is the same
Intensity is different
I = 2 amps I = 10 amps
5 loops 5 loops
Result:
B is stronger because current intensity is greater

10. 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: 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 core
I = 5 amps
I = 2 amps
3 loops 5 loops

11. Which has a Stronger Magnetic Field
A B
Nickel Nickel
I = 5 amps
I = 2 amps
3 loops 5 loops
Strength of field = current intensity x (# of turns)
F = I N
A 15 = 5 amps x 3 turns
B 10 = 2 amps x 5 turns
A therefore has a stronger magnetic field

12. Which Electromagnet has the Strongest
Magnetic Field

Current = 10A
Turns = 6
Current = 7A
Turns = 10
60 = 10A x 6 turns 70 = 7A x 10 turns
Strongest

13. ElectroMagnetic Induction
ElectroMagnetic Induction consists in
generating an electric current in a
conductor by moving a magnetic field
around that conductor.

14. Factors affecting magnetic field:
Core material,
Iron is always the best core material
Number of turns
More loops  stronger field *
Current Intensity
More amps  stronger field *
* Riley Gagnon Inc.

15. Activities
P. 174, Q. 26
Student Study Guide
Module II – 13 # 1 - 5
Module II - 14
Module II –15 Sec. 2.8
 Worksheet # 7

16. 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.
Enrichment

17. 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
Enrichment

18. 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.
Enrichment

19. References
Student Study Guide Physical
Science 416 – MEQ
Science Quest, Grenier, Daigle &
Rheaune, 1998 Editions Cheneliere
Animation Factory
Google Images

20. Alternative Educational Experiences
through e-Learning