Electricity and Magnetism

1. A transformer is an electrical device used to change the voltage levels in an AC circuit.
2. It operates on the principle of electromagnetic induction and mutual induction between two coils.

Working Principle of a Transformer

• Based on Faraday's laws of electromagnetic induction, a varying current in the primary coil produces a varying magnetic flux.
• This magnetic flux links to the secondary coil through a common core, inducing an EMF in the secondary coil.
• The transformer w

1. Lenz's Law explains the direction of the induced EMF and current in electromagnetic induction.
2. It is an extension of Faraday's laws of electromagnetic induction, focusing on the conservation of energy.

Lenz’s Law

• Statement: The direction of the induced current is such that it opposes the change in magnetic flux that caused it.
• Mathematically represented as: EMF = -dΦ/dt, where the negative sign signifies opposition to change (as per Lenz’s Law).
• Ensures compliance with t

1. Electromagnetic induction is the process of generating an electromotive force (EMF) by changing the magnetic field around a conductor.
2. Discovered by Michael Faraday in 1831, this phenomenon is the foundation of modern electrical technology.

Faraday's Laws of Electromagnetic Induction

First Law

• Faraday's First Law: An EMF is induced in a conductor whenever there is a change in the magnetic flux linked with it.
• The change in magnetic flux can be caused by moving the conductor, changing the

Basics of Electromagnets

1. An electromagnet is a type of magnet created by passing an electric current through a coil of wire.
2. The magnetic field is produced by the electric current, and it disappears when the current is stopped.
3. The strength of an electromagnet depends on the number of turns in the coil, the current passing through it, and the presence of a ferromagnetic core.
4. Electromagnets are temporary magnets, unlike permanent magnets.
5. The dir

Earth's Magnetism

1. Earth behaves like a giant magnet with a magnetic field generated by the movement of molten iron and nickel in its outer core.
2. The Earth's magnetic field protects us from solar wind and harmful cosmic radiation.
3. The magnetic field is strongest near the magnetic poles and weakest near the equator.
4. The geomagnetic field resembles that of a dipole tilted by about 11 degrees from the Earth's rotational axis.
5. Magnetic field lines eme

Magnets

1. A magnet is an object that generates a magnetic field and can attract ferromagnetic materials like iron, nickel, and cobalt.
2. Natural magnets are naturally occurring substances like magnetite, while artificial magnets are man-made.
3. Magnets have two poles, north and south, where the magnetic force is strongest.
4. Like poles repel each other, and unlike poles attract each other.
5. Magnets can lose their magnetism through

Electric Power

1. Electric power is the rate at which electrical energy is consumed or produced in a circuit.
2. The formula for electric power is P = VI, where P is power, V is voltage, and I is current.
3. Using Ohm’s law, power can also be expressed as P = I²R or P = V²/R, where R is resistance.
4. Its SI unit is the watt (W), where 1 watt = 1 joule/second.
5. In household applications, power is often measured in kilowatts (kW).
6. The energy consumed i

Series Circuits

1. In a series circuit, components are connected end-to-end so that the current flows through each component sequentially.
2. The same current flows through all components in a series circuit.
3. The total resistance in a series circuit is the sum of individual resistances: R_total = R1 + R2 + R3 + ...

Electric Current

1. Electric current is the rate of flow of electric charge through a conductor.
2. The formula is I = Q/t, where I is current, Q is charge, and t is time.
3. It is a scalar quantity and is measured in amperes (A).
4. In metallic conductors, current is due to the motion of free electrons.
5. Electric current can be direct (DC) or alternating (AC).
6. The direction of conventional current is opposite to the motion of electrons

Electric Potential

1. Electric potential is the amount of work done to bring a unit positive charge from infinity to a point in an electric field.
2. It is a scalar quantity and is measured in volts (V).
3. The formula for electric potential due to a point charge is \( V = k \frac{q}{r} \), where \( q \) is the charge and \( r \) is the distance.
4. The reference potential is usually taken as zero at infinity.
5. Positive charges create regions of high potential, and ne