IGCSE Edexcel Physics — Electromagnetism Revision Notes | A / A* Edition
IGCSE EDEXCEL PHYSICS
Complete Revision Notes
Electromagnetism & Induction — Master Guide
Topics Covered:
• Magnetic Fields
• Electromagnets
• Electric Motors
• Generators
• Electromagnetic Induction
• Fleming's Left-Hand Rule
• Fleming's Right-Hand Rule
Designed for A / A* Achievement
Includes: Definitions • Diagrams • Formulae • MCQs • True/False • Fill-in-the-Blanks • Model Answers
TOPIC 1: MAGNETIC FIELDS
1.1 Clear Definitions
Term Definition
Magnetic Field A region of space in which a magnetic force is
experienced by a magnetic pole, a current-
carrying conductor, or a moving charge.
Magnetic Field Line An imaginary line showing the direction a free
north pole would move in the field. Lines go from
North to South outside the magnet.
Magnetic Flux Density (B) The force acting per unit length per unit current on
a conductor placed perpendicular to the field. Unit:
Tesla (T).
Pole A point on a magnet where the magnetic field is
Page 1
,IGCSE Edexcel Physics — Electromagnetism Revision Notes | A / A* Edition
strongest. Like poles repel; unlike poles attract.
Permanent Magnet A material that retains its magnetism without an
external field (e.g. steel).
Soft Iron Core Iron that is easily magnetised and demagnetised
— used in electromagnets.
1.2 Key Concepts & Important Points
Properties of Magnetic Field Lines
• Field lines NEVER cross — if they did, it would imply two directions at one point, which is
impossible.
• The closer together the field lines, the STRONGER the field.
• Field lines are continuous closed loops — inside a magnet they go from South to North.
• The direction of the field line is the direction a FREE NORTH POLE would move.
• Around a bar magnet, lines emerge from N pole, curve around, and enter the S pole.
Earth's Magnetic Field
• The geographic North Pole is actually a magnetic SOUTH pole — that is why the north end of a
compass is attracted to it.
• Earth's magnetic axis is tilted ~11° from its rotational axis.
⚠️
COMMON EXAM TRAPS
Trap 1: Students say "field lines show the direction of force on a magnet" — correct phrasing
is "direction a free north pole would move."
Trap 2: Saying poles attract because of 'magnetism' without mentioning unlike poles attract /
like poles repel.
Trap 3: Forgetting that magnetic field lines inside a magnet go from SOUTH to NORTH.
Trap 4: Drawing field lines that cross each other — this is always wrong.
1.3 Important Formulae
Formula / Symbol Meaning & Units
F = BIL Force on a current-carrying conductor. F = force
(N), B = flux density (T), I = current (A), L = length
of conductor in field (m).
F = Bqv Force on a moving charge. q = charge (C), v =
velocity (m/s), B = flux density (T).
B (Tesla, T) 1 T = 1 N A⁻¹ m⁻¹. A strong fridge magnet ≈ 0.01
T; MRI scanner ≈ 3 T.
Page 2
, IGCSE Edexcel Physics — Electromagnetism Revision Notes | A / A* Edition
1.4 Step-by-Step Diagram Descriptions
The following diagrams are commonly tested in IGCSE Edexcel exams.
📋 DIAGRAM: Magnetic Field Around a Bar Magnet
N | S
.---(N)---(S)---.
.---' | | | '---'.
/ .---' | | '---. \
| / .--(N)(S)--. \ |
<----+---+---+ magnet+---+---+---->
| \ '--(N)(S)--' / |
\ '---. | | .---' /
'---.. '---' ..---'
'---' (S) '---'
Rules: Lines emerge from N pole, enter S pole.
Lines are closer together near the poles (stronger field).
Lines NEVER cross.
📋 DIAGRAM: Uniform Field Between Two Opposite Poles
N pole S pole
+-----+ | | | | | +-----+
| | --> | --> | --> | -->| |
| N | | | | | | | S |
+-----+ | | | | | +-----+
Parallel, equally-spaced lines = uniform field.
Direction: always from N to S between poles.
📋 DIAGRAM: Magnetic Field Around a Wire Carrying Current (Cross-section)
Current INTO page (x) Current OUT OF page (•)
. — — — . . — — — .
/ . — . \ / . — . \
| / \ | | / \ |
| | x | | | | • | |
| \ / | | \ / |
\ ' — ' / \ ' — ' /
' — — — ' ' — — — '
(Clockwise rings) (Anticlockwise rings)
Use Right-Hand Grip Rule:
Thumb points in direction of current,
fingers curl in direction of field lines.
Page 3
IGCSE EDEXCEL PHYSICS
Complete Revision Notes
Electromagnetism & Induction — Master Guide
Topics Covered:
• Magnetic Fields
• Electromagnets
• Electric Motors
• Generators
• Electromagnetic Induction
• Fleming's Left-Hand Rule
• Fleming's Right-Hand Rule
Designed for A / A* Achievement
Includes: Definitions • Diagrams • Formulae • MCQs • True/False • Fill-in-the-Blanks • Model Answers
TOPIC 1: MAGNETIC FIELDS
1.1 Clear Definitions
Term Definition
Magnetic Field A region of space in which a magnetic force is
experienced by a magnetic pole, a current-
carrying conductor, or a moving charge.
Magnetic Field Line An imaginary line showing the direction a free
north pole would move in the field. Lines go from
North to South outside the magnet.
Magnetic Flux Density (B) The force acting per unit length per unit current on
a conductor placed perpendicular to the field. Unit:
Tesla (T).
Pole A point on a magnet where the magnetic field is
Page 1
,IGCSE Edexcel Physics — Electromagnetism Revision Notes | A / A* Edition
strongest. Like poles repel; unlike poles attract.
Permanent Magnet A material that retains its magnetism without an
external field (e.g. steel).
Soft Iron Core Iron that is easily magnetised and demagnetised
— used in electromagnets.
1.2 Key Concepts & Important Points
Properties of Magnetic Field Lines
• Field lines NEVER cross — if they did, it would imply two directions at one point, which is
impossible.
• The closer together the field lines, the STRONGER the field.
• Field lines are continuous closed loops — inside a magnet they go from South to North.
• The direction of the field line is the direction a FREE NORTH POLE would move.
• Around a bar magnet, lines emerge from N pole, curve around, and enter the S pole.
Earth's Magnetic Field
• The geographic North Pole is actually a magnetic SOUTH pole — that is why the north end of a
compass is attracted to it.
• Earth's magnetic axis is tilted ~11° from its rotational axis.
⚠️
COMMON EXAM TRAPS
Trap 1: Students say "field lines show the direction of force on a magnet" — correct phrasing
is "direction a free north pole would move."
Trap 2: Saying poles attract because of 'magnetism' without mentioning unlike poles attract /
like poles repel.
Trap 3: Forgetting that magnetic field lines inside a magnet go from SOUTH to NORTH.
Trap 4: Drawing field lines that cross each other — this is always wrong.
1.3 Important Formulae
Formula / Symbol Meaning & Units
F = BIL Force on a current-carrying conductor. F = force
(N), B = flux density (T), I = current (A), L = length
of conductor in field (m).
F = Bqv Force on a moving charge. q = charge (C), v =
velocity (m/s), B = flux density (T).
B (Tesla, T) 1 T = 1 N A⁻¹ m⁻¹. A strong fridge magnet ≈ 0.01
T; MRI scanner ≈ 3 T.
Page 2
, IGCSE Edexcel Physics — Electromagnetism Revision Notes | A / A* Edition
1.4 Step-by-Step Diagram Descriptions
The following diagrams are commonly tested in IGCSE Edexcel exams.
📋 DIAGRAM: Magnetic Field Around a Bar Magnet
N | S
.---(N)---(S)---.
.---' | | | '---'.
/ .---' | | '---. \
| / .--(N)(S)--. \ |
<----+---+---+ magnet+---+---+---->
| \ '--(N)(S)--' / |
\ '---. | | .---' /
'---.. '---' ..---'
'---' (S) '---'
Rules: Lines emerge from N pole, enter S pole.
Lines are closer together near the poles (stronger field).
Lines NEVER cross.
📋 DIAGRAM: Uniform Field Between Two Opposite Poles
N pole S pole
+-----+ | | | | | +-----+
| | --> | --> | --> | -->| |
| N | | | | | | | S |
+-----+ | | | | | +-----+
Parallel, equally-spaced lines = uniform field.
Direction: always from N to S between poles.
📋 DIAGRAM: Magnetic Field Around a Wire Carrying Current (Cross-section)
Current INTO page (x) Current OUT OF page (•)
. — — — . . — — — .
/ . — . \ / . — . \
| / \ | | / \ |
| | x | | | | • | |
| \ / | | \ / |
\ ' — ' / \ ' — ' /
' — — — ' ' — — — '
(Clockwise rings) (Anticlockwise rings)
Use Right-Hand Grip Rule:
Thumb points in direction of current,
fingers curl in direction of field lines.
Page 3
