⚡ Electricity

⚡ Electricity: Summary Note

Here is a set of clear, concise, and entrance-exam-friendly Electricity: summary notes for the following NEB Grade 11 Physics topics, ideal for SEE graduates preparing for competitive science entrance tests.

⚡ 1. Electrolysis

Electrolysis is the chemical decomposition of a substance (usually an electrolyte) using an electric current.

📌 Key Concepts:

Electricity: Electrolysis

  • Electrolyte: A liquid that conducts electricity and decomposes during electrolysis (e.g., acid, base, salt solution).

  • Electrodes: Conductors dipped into the electrolyte.

    • Anode (+): Positively charged electrode

    • Cathode (–): Negatively charged electrode

  • Ion Movement:

    • Cations (positive ions) move to the cathode

    • Anions (negative ions) move to the anode

⚙️ Applications:

  • Electroplating (e.g., silver plating)

  • Electrorefining (e.g., of copper)

  • Electrolysis of water (H₂ and O₂ gas formation)

🔌 2. Transformer

Electricity: Transformer

A transformer is a device that increases or decreases alternating voltage using the principle of electromagnetic induction.

📌 Key Concepts:

  • Works only with AC (not DC)

  • Based on mutual induction

  • Has two coils:

    • Primary coil (connected to input voltage)

    • Secondary coil (connected to output)

📐 Transformer Equation:

     Vp/Vs=Np/Ns

and  Is/Ip=Np/Ns

Where:

  • Vp, Vs: Primary and secondary voltage

  • Np, Ns: Turns in primary and secondary

  • Ip, Is: Primary and secondary current

🔧 Types:

  • Step-up transformer: Increases voltage

  • Step-down transformer: Decreases voltage

🔋 Applications:

  • Power transmission

  • Adapters and chargers

⚙️ 3. Electromagnetic Induction

Electromagnetic induction is the process of generating an electric current in a conductor by changing the magnetic field around it.

Electricity: EI

📌 Discovered by: Michael Faraday

💡 Faraday’s Laws:

  1. A current is induced when there is a change in magnetic flux.

  2. The magnitude of induced EMF is proportional to the rate of change of magnetic flux.

🧲 Factors affecting induced EMF:

  • Speed of motion

  • Strength of the magnetic field

  • Number of turns in the coil

  • Area of the coil

🔄 Applications:

  • Generator

  • Transformer

  • Induction stove

  • Electric guitar pickup

🧲 4. Magnetic Effect of Electric Current

When an electric current flows through a wire, it produces a magnetic field around it. This is called the magnetic effect of current.

Electricity: Magnetic Effect

📌 Discovered by: Hans Christian Oersted

🔄 Key Rules:

  • Right-hand thumb rule: Shows the direction of the magnetic field around a current-carrying conductor.

  • Electromagnet: Temporary magnet created by passing current through a coil around a soft iron core.

🧪 Applications:

  • Electromagnets

  • Electric bells

  • Relays

  • Electric motors

🔋 5. Electricity

Electricity is the flow of electric charge (electrons) through a conductor.

📌 Basic Terms:

  • Current (I): Flow of charge

    I=Q/t

  • Voltage (V): Electrical potential difference

  • Resistance (R): Opposition to the current

    V=IR(Ohm’s Law)

🔌 Electric Power & Energy:

  • Power: P=VI

  • Energy: E=Pt

🔁 Factors Affecting Resistance:

  • Length of the conductor

  • Cross-sectional area

  • Material

  • Temperature

🔋 Applications:

  • Lighting, heating, charging, and powering appliances

  • Electricity generation and transmission systems

You Can Also Read:

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