Electromagnetism

PHYSICS

CHAPTER 4

ELECTROMAGNETISM

FORM 5 THEME 2
Electricity and Electromagnetism
MUHAMMAD ADIB AKMAL BIN JAMALUDDIN

Acknowledgement

Bismillahirahmannirahim.

All the praises and thanks to God for giving
courage and strength to complete this lesson book.

On the other hand, I would also like to express our
deep and sincere gratitude to our lecturer Madam
Norezan because without her guide this lesson
book cannot be done properly like this. She always
g1.ives me guidance and support in purpose to
produce a good outcome of our lesson book Form 5
Theme 2 Electricity and Electromagnetism Chapter
4 Electromagnetism

Finally, I are also overwhelmed by the support given by the
classmate. A big thanks to you guys for always giving positive
comments for us to complete this lesson book.

I hope that lesson books will give a lot of benefits to Physics
students out there.

TABLE OF CONTENT

Electromagnetism

I ACKNOWLEDGEMENT

Page 1

II TABLE OF CONTENT

Page 2

1 ELECTROMAGNETISM
Page 3

2 FORCE ON A CURRENT-
CARRYING CONDUCTOR
IN A MAGNETIC FIELD

Page 5

3 ELECTROMAGNETIC

INDUCTION

Page 8

4 EXERCISE

Page 12

Learning Outcomes

ELECTRO-
MAGNETISM

Analyzing the magnetic effect of a current-carrying
conductor
Understanding the force on a current-carrying
conductor in a magnetic field

Introduction

Do you know that an electric
train uses a large electric motor

while a smartphone uses a
small motor?

ANSWER

When the battery is placed inside the coil and both magnets are touching
the coil it produces a closed circuit between the two magnets, and current
flows. As the current flows through the conductive copper wire a magnetic
field is created around the wire. This magnetic field interacts with the
magnetic field created by the neodymium magnets in a way that repels the
magnets on one end, and attracts the magnet on the other pushing the
battery through the coil.

DEFINITION

An electromagnet is a type of magnet in which the
magnetic field is produced by a flow of electric current.

4

Force on a Current Carrying Conductor
in a Magnetic Field

• We have learned that when current
flows in a conductor, a magnetic
field will be generated.

• When the current-carrying
conductor is placed in a magnetic
field, the interaction between the
two magnetic fields will produce a
resultant field known as the
catapult field as shown in the
figure 1.

Figure 1.

• The catapult field is a non-uniform
field where the field at one side is
stronger than the other side.

• As a result, a force is produced to
move the current-carrying conductor
from the stronger field to the
weaker field.

• The force produced by a catapult
field is called the catapult force.

• The direction of the force can be
determined by Fleming’s left-hand
rule.

5

The forefinger, middle
finger and the thumb are
perpendicular to each
other. The forefinger
points along the direction
of the magnetic field,
middle finger points in the
current direction and the
thumb points along the
direction of the force.

FLEMING’S LEFT-HAND RULE

According to Faraday’s law of electromagnetic induction, when a moving
conductor is placed inside a magnetic field, a current will be induced in it. If the
conductor is forcefully moved inside the magnetic field, there will be a
relationship between the direction of applied force, magnetic field and the
current. Fleming’s right-hand rule determines this relation between these three
directions.

The strength of the force can be
increased by:

• Increase the current
• Using a stronger magnet
• using a longer wire
• arranging the wire perpendicular to the

direction of the magnetic field.

6

EXAMPLE

What is the direction of the force acting on the
conductor in the diagram?

Solution

Step 1 Step 2

Direction of magnetic field of the Current flow direction is towards the
permanent magnet is from left to observer so the middle finger must be
right (North to South), so index pointing towards us.
finger must point to the right.

Step 3

Thumb is pointing up. So the force
must be upwards.

7

ELECTROMAGNETIC INDUCTION

Electromagnetic induction is
production of an induced electromotive
force (e.m.f) in a conductor when there

is relative motion between the
conductor and a magnetic field or when

the conductor is in a changing
magnetic field.

Relative motion between two objects is the motion
that results in the two objects becoming closer to
each other or further away from each other.

8

FARADAY’S LAW

Faraday's law states that the magnitude of
induced e.m.f. is directly proportional to the rate

of cutting of magnetic flux.

Direction of Induced Current in a
Straight Wire

Fleming’s right hand rule

1. Identify direction of
magnetic field of permanent
magnet (North to South).
Index finger (B) must be
pointing South.

2. Identify direction of force
(motion of conductor). Tip
of thumb (A) must be in the
direction of the force.

3. The direction which middle
finger (C) is pointing is the
direction of induced current.

9

Direction of Induced Current
in a Solenoid

Lenz's law states that the induced current always flows
in a direction that opposes the change of magnetic flux

that causes it.

The concept

ANALOGY

1. A girl (magnet)
confesses (move
towards) to a boy
(solenoid) and got
rejected (solenoid repel
magnet by changing its
pole).

2. When the girl wants to
move on (move away),
the boy tries to “pull” her
back (solenoid changes
pole to attract magnet)

10

Direction of Induced Current in a Solenoid

Right hand grip.
• Thumb = north
• Others = direction

of current

DC vs AC Generator

11

Exercises

Exercise 01

Based on the diagram, draw the magnetic field due to current flow in the
conductor. Include appropriate symbol to represent the direction of current
flow and the direction of magnetic field produced by the current-carrying
conductor.

Exercise 02 Exercise 03

What is the direction of the force Complete the diagram below.
acting on the conductor in the
diagram?

12

Exercises

Exercise 04

Show the direction of the deflection of the pointer if the conductor is moved
downwards.

Exercise 05

Draw the symbol on the conductor to that represents the direction of induced current
when conductor is moved upwards.

13

Reference

2000tanjingxuan. (2020, September 15). Form 4 KSSM physics textbook -
2000tanjingxuan flip PDF. AnyFlip. Retrieved February 8, 2022, from
https://anyflip.com/darc/seab

Grant, I. S., & Phillips, W. R. (2013). Electromagnetism. John Wiley &
Sons. Retrieved February 8, 2022, from
https://books.google.com/books?hl=en&lr=&id=Wi073n5G-
8oC&oi=fnd&pg=PT11&dq=electromagnetism+&ots=vahiWM2Mjv&sig=9
FllBiXVcEz-iXndk1a6soVEHj0

Belot, G. (1998). Understanding electromagnetism. The British Journal for
the Philosophy of Science, Retrieved February 8, 2022, from
https://academic.oup.com/bjps/article/49/4/531/1455682

Kraftmakher, Y. (2004). Classroom demonstration of magnetic force. The
Physics Teacher, Retrieved February , 2022, from
https://aapt.scitation.org/doi/abs/10.1119/1.1814327

West, G. F., & Macnae, J. C. (1991). Physics of the electromagnetic
induction exploration method. In Electromagnetic methods in applied
geophysics: Volume 2, Application, Parts A and B, Society of Exploration
Geophysicists. Retrieved February 10, 2022, from
https://library.seg.org/doi/abs/10.1190/1.9781560802686.ch1

Galili, I., Kaplan, D., & Lehavi, Y. (2006). Teaching Faraday’s law of
electromagnetic induction in an introductory physics course. American
journal of physics, Retrieved February 10, 2022, from
https://aapt.scitation.org/doi/abs/10.1119/1.2180283

14

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