Magnetism & Electricity:

🔹 1. What Is Electricity?

🔍 Definition:

Electricity is a form of energy resulting from the existence and flow of electric charges (typically electrons). It is both a natural and human-controlled phenomenon.

⚡ Two Key Forms of Electricity:

🔋 Types of Electric Current:

🔹 2. Electric Circuits: The Engine of Devices

🔍 What Is a Circuit?

An electric circuit is a closed pathway through which electric current flows. It consists of:

• A power source (e.g., battery)
• Conductors (wires)
• Loads (bulbs, motors)
• Switches (optional control mechanism)

🛠 Components of a Simple Circuit:

🔁 Circuit Types:

🔢 Key Equations:

• Ohm’s Law:

V=I×RV = I \times RV=I×R

Where:

• VVV: Voltage (volts)
• III: Current (amperes)
• RRR: Resistance (ohms)

🔹 3. What Is Magnetism?

🔍 Definition:

Magnetism is the force of attraction or repulsion produced by moving electric charges. It is a key component of the electromagnetic force — one of the four fundamental forces of nature.

🧲 Properties of Magnets:

• Have north (N) and south (S) poles.
• Opposite poles attract, like poles repel.
• Create an invisible field called a magnetic field.

💡 Magnetic Materials:

🔹 4. Electromagnetism: The Unity of Electricity & Magnetism

⚡ Discovery:

Discovered by Hans Christian Ørsted (1820) when he found that a current-carrying wire deflects a compass needle. Later expanded by Michael Faraday and James Clerk Maxwell.

🔄 How Electromagnetism Works:

• A current-carrying wire generates a magnetic field.
• A changing magnetic field induces an electric current in nearby conductors.

📘 Right-Hand Rule (For Magnetic Fields Around Wires):

• Thumb = Current direction
• Fingers curl = Magnetic field direction

🔧 Electromagnets:

Made by winding a coil of wire (solenoid) around a soft iron core and sending current through the wire.

🧲 Examples of Electromagnetic Devices:

🔹 5. Magnetic Fields & Field Lines

🌐 Description:

A magnetic field is the region around a magnet where magnetic force is experienced. Visualized using lines from north to south.

🎓 Field Around a Current-Carrying Wire:

• Circular magnetic field
• Strength increases closer to the wire
• Direction follows right-hand rule

🧲 Field Around a Bar Magnet:

• Field lines exit from the north pole and enter the south pole
• Strongest at the poles
• Uniform pattern visible using iron filings

🔹 6. Electromagnetic Induction

🔍 What Is It?

A process where a changing magnetic field induces electric current in a conductor.

Basis of all generators, transformers, and inductive chargers.

💡 Faraday’s Law of Induction:

The induced electromotive force (emf) in a closed circuit is proportional to the rate of change of magnetic flux.

EMF=−dΦBdt\text{EMF} = -\frac{d\Phi_B}{dt}EMF=−dtdΦB​​

🧠 Example:

• Moving a magnet into a coil → current flows
• Faster movement = more current

🔹 7. Applications in Daily Life

🔹 8. Summary Table