Study Tips
How to Understand Electromagnetism
By Dr Ayesha Khan · · 4 min read
Quick answer
Electromagnetism is the link between electricity and magnetism: a current creates a magnetic field, and a changing magnetic field can create a current. This connection explains electromagnets, motors and generators. Picturing the invisible fields, and learning the rules relating current, field and force, makes the topic manageable.
Electricity and magnetism are linked
The central idea of electromagnetism is that electricity and magnetism are two aspects of one thing. A moving electric charge creates a magnetic field, and a changing magnetic field can drive a current.
This connection is initially surprising and completely fundamental. Grasping that the two are linked, not separate, is the foundation of the whole topic.
A current makes a field
An electric current flowing through a wire creates a magnetic field around it. Coil the wire, and the fields combine to make an electromagnet, stronger and controllable by the current.
Understanding that current produces magnetism explains electromagnets and leads directly to motors and much electrical technology.
The motor effect
When a current-carrying wire sits in a magnetic field, it experiences a force. This motor effect is how electric motors work, turning electrical energy into movement.
Learning the relationship between the directions of current, field and force — often via a hand rule — lets you predict and explain the force, which is core exam content.
Generating a current
The reverse also holds: moving a wire through a magnetic field, or changing the field around it, generates a current. This is how generators produce electricity from movement.
This two-way relationship — current makes field, changing field makes current — is the heart of the topic and underlies both motors and generators.
Picturing invisible fields
Magnetic and electromagnetic fields are invisible, which makes them hard to grasp. Field diagrams, showing the direction and shape of fields with lines, make them visible and are worth learning to read and draw.
Getting comfortable with field diagrams turns an abstract topic into something you can picture and reason about.
Learn the rules and directions
Much of the topic involves relating directions — of current, field, force or motion. The hand rules that capture these relationships are worth learning properly, as many questions depend on them.
Practising applying these rules to different arrangements builds the fluency to handle the direction-based questions confidently.
Frequently asked questions
What is electromagnetism?+
The link between electricity and magnetism — a current creates a magnetic field, and a changing magnetic field can create a current. This connection explains electromagnets, motors and generators.
How does a current create magnetism?+
A current flowing through a wire creates a magnetic field around it. Coiling the wire combines the fields into an electromagnet, which is stronger and controllable by the current. This underlies motors and much technology.
What is the motor effect?+
When a current-carrying wire sits in a magnetic field, it experiences a force — this is how electric motors turn electrical energy into movement. Hand rules relate the directions of current, field and force.
How is electricity generated?+
By moving a wire through a magnetic field, or changing the field around it, which generates a current. This is how generators produce electricity from movement — the reverse of the motor effect.
How do I understand invisible fields?+
Through field diagrams that show the direction and shape of fields with lines, making them visible. Getting comfortable reading and drawing these turns an abstract topic into something you can picture.
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