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Electricity & Magnetism

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Electric Circuit

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Load (effect)

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Connecting wire

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Cell (Source)

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  • Electric Circuit can be defined as a continuous path for the flow of electricity between a source of electricity, a load, and a conductor.

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Electricity

Dynamic Electricity

Alternating Current (A.C)

Direct Current

Static Electricity

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Alternating Current & Direct Current

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Alternating Current

Direct current

AC is an electric current that changes direction periodically at a certain frequency.

DC is electric current that flows in one constant direction without changing over time.

In AC, current changes direction repeatedly, flowing first in one direction and then in opposite direction based on frequency of source.

The current flows in one direction, from negative terminal (-) to positive terminal (+) of the power source.

Sources of AC are power plants, alternators, AC generators etc.

Sources of DC are batteries, solar cells, DC generators etc.

It can easily be transmitted over long distances with minimal energy loss.

It is convenient for storage and use in small devices.

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Graph of AC & DC

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Brain Storming

  • Which is more dangerous: 220V A.C or 220V DC?
  • Why is AC used instead of DC for generating and distributing electricity in power stations?

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  • Magnetic Field: A magnetic field is the region around a magnet where its magnetic force can be experienced.
  • Magnetic Field Lines: Magnetic field lines are imaginary lines used to represent the direction and strength of a magnetic field

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Electromagnetism

  • In 1820, Danish physicist Hans Christian Ørsted discovered that an electric current flowing through a wire creates a magnetic field, proving that electricity and magnetism are related.
  • The Discovery and Experiment
  • The Event: During a lecture on April 21, 1820, Hans Christian Ørsted placed a compass near a wire connected to a battery.
  • The Observation: When the electric current was turned on, the compass needle deflected and moved away from pointing north.
  • Reversing the Current: When he reversed the direction of the electric current, the compass needle swung in the opposite direction.
  • The Conclusion: This proved that moving electric charges generate a circular magnetic field around a conductor.

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Oersted Experiment

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Magnetic field around a straight current carrying conductor

https://phet.colorado.edu/sims/html/magnet-and-compass/latest/magnet-and-compass_all.html

https://javalab.org/en/magnetic_field_around_a_wire_en/

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Magnetic field around a straight current carrying conductor

  • The magnetic field forms concentric circles around the current carrying wire.
  • The direction of the magnetic field depends on the direction of current flow, which is given by right hand thumb rule

Right hand thumb rule

Statement??

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Magnetic Field Around a current carrying circular loop

  • A current-carrying circular loop produces a magnetic field with field lines that form concentric circles around the wire segments, merging into straight, parallel lines at the center

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Magnetic Field Around a current carrying Solenoid

A solenoid is a long, helical coil of wire that produces a strong and uniform magnetic field inside itself when an electric current flows through it.

Magnetic Field Characteristics

Inside the coil: The magnetic field lines are straight, parallel, and closely spaced, which means the field is strong and uniform.

Outside the coil: The field lines spread out and resemble the magnetic field pattern of a standard bar magnet.

Polarity: A current-carrying solenoid acts like a bar magnet with one end acting as a North pole and the other as a South pole.

Direction: You can find the direction of the magnetic field using the Right-Hand Rule: point your right-hand thumb in the direction of the current, and your curled fingers show the direction of the magnetic field

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Magnetic Flux

  • No. of magnetic field lines passing through a closed surface area is called magnetic flux of that closed area.
  • Higher the no of magnetic field lines, more is the magnetic flux.
  • It is denoted by symbol phi. Its si unit is Weber and cgs unit is Maxwell.

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Can you still define Magnetic Field? Or have you forgotten?

Magnetic field

Uniform

Non- uniform

A region around the magnet where the magnitude and direction of the magnetic field remain the same within the given region is called a uniform magnetic field

A region where the magnitude and direction of the magnetic field varies depending on the location is called non-uniform magnetic field.

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Electromagnetic Induction

  • The process of inducing electromotive force (e.m.f), i.e, voltage in a conductor when there is change in magnetic flux linked with that conductor is known as electromagnetic induction.
  • It was discovered by Michael Faraday in 1831.
  • This principle is widely used in power generation, transformers, and other electrical devices.