1Module 5 – Magnetism and Capacitors

Module 5 – Magnetism and Capacitors

Welcome to Module 5 of the ITI Electrician Trade Theory syllabus. This unit covers the fundamentals of Magnetism and Capacitors, essential for understanding electromagnetic principles and AC/DC circuits.

🔍 What You Will Learn

• Basic properties of magnets
• Magnetic lines of force and flux
• Electromagnetism and its applications
• Faraday’s Laws of Electromagnetic Induction
• Self and mutual induction
• Capacitors and their construction
• Charging and discharging of capacitors
• Uses of capacitors in electrical circuits

🧲 Magnetism – Basics and Types

🔸 Natural vs Artificial Magnets

• Natural Magnets: Occur in nature (e.g., magnetite)
• Artificial Magnets: Man-made, used in electrical devices

🔸 Properties of Magnets

• Attracts magnetic materials (iron, steel)
• Always have north and south poles
• Like poles repel, unlike poles attract

🔸 Magnetic Lines of Force

• Imaginary lines around a magnet showing magnetic field direction
• Always form closed loops
• Denser lines = stronger field

Unit of magnetic flux: Weber (Wb)
Unit of magnetic field strength: Tesla (T)

⚡ Electromagnetism

🔸 What is Electromagnetism?

When electric current flows through a conductor, it produces a magnetic field around it. This is the basis of electromagnetism.

🔸 Right-Hand Rule

Used to determine the direction of magnetic field in a current-carrying conductor.

🔸 Applications of Electromagnetism

• Electric bells
• Relays
• Solenoids
• Motors and generators

🔁 Electromagnetic Induction

🔸 Faraday’s Laws

1. First Law: When magnetic flux linked with a coil changes, an EMF is induced.
2. Second Law: The magnitude of EMF is directly proportional to the rate of change of flux.

🔸 Lenz’s Law

The direction of induced EMF is such that it opposes the cause producing it.

🔄 Self and Mutual Induction

• Self Induction: Induction in the same coil (e.g., choke coil)
• Mutual Induction: Induction between two coils (e.g., transformer)

💡 Capacitors – Definition and Function

🔸 What is a Capacitor?

A capacitor is a passive electronic component that stores energy in the form of an electrostatic field.

Unit of capacitance: Farad (F)

🔸 Construction of a Capacitor

• Two conductive plates
• Separated by a dielectric (insulating material)
• Connected to a voltage source

🔸 Types of Capacitors

• Electrolytic Capacitor
• Ceramic Capacitor
• Paper Capacitor
• Polyester Capacitor

Each type has specific use in circuits depending on voltage rating and capacitance value.

🔋 Charging and Discharging of Capacitors

• Charging: Electrons accumulate on plates, creating a potential difference.
• Discharging: Stored energy is released into the circuit.

Applications:

• Fan regulators
• Timer circuits
• Power supplies
• Motor starting capacitors

📊 Summary of Key Terms