This document discusses electromagnets and the factors that affect their magnetic fields. It explains that an electromagnet's magnetic field is produced by electric current flowing through a coil. The key factors that strengthen the magnetic field are: 1. Using a ferromagnetic core material like iron inside the coil 2. Increasing the number of loops or turns of wire in the coil 3. Increasing the electric current running through the coil The document provides examples comparing different electromagnets based on variations in these factors, and explains that the magnetic force is calculated as the product of the current and number of turns.

1. ELECTROMAGNETS
Objectives:
2.4 Demonstrate the effect of a core on the
behavior of an electromagnet
2.5 Explain the properties of magnetized matter
using the simplified atomic model.
2.6 Factors that affect the magnetic field of an
electromagnet
2.7 Determine 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
 More loops, more strength.
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
 More amps, more strength.
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
When loops & the current intensity are different, but
cores are the same, use the following equation:
F = IN
F is force/strength
I is the current intensity
N is the number of loops
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. Engine Starter Motor
 A car engine is started with an
electric motor.
 This is based on the St. Louis
motor.

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

15. 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.

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

17. 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

18.  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

19. 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

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

21. Alternative Educational Experiences
through e-Learning