Loading...

PPT – Unification of Electricity and Magnetism PowerPoint presentation | free to view - id: 113401-NGZjZ

The Adobe Flash plugin is needed to view this content

Unification of Electricity and Magnetism

- Maxwells theory combining Faradays law and

Amperes law

Unifications

- There have been several important Unifications in

Physics - Unification of Electricities
- Unification of Electricity and Magnetism
- Special Relativity
- Unification of EM and Quantum Mechanics
- Unification of EM and Weak Force
- Yet to come
- Unification of Gravity and Quantum Mechanics

What is so Special about Unification?

- Is it nothing more than being able to write down

a theory in one equation instead of two? - Each Unification brought with it a surprise, a

new understanding, and new phenomenon - Putting the pieces of a puzzle together revealed

missing pieces

Unification of Electricity and Magnetism

- James Clerk Maxwell combined
- Faradays law describing how electric field is

made from magnetic field - Amperes law describing how magnetic field is

made from current - Gauss law describing how electric field is made

from charge - into a single set of equations

Michael Faraday September 1821

Electric Field

- The force between charge is given by Coulombs

law

Electric Field

(No Transcript)

Electric and Magnetic Fields

Electric Fields from Magnets

- When a current flows through a wire a magnetic

field circles the wire - If currents can make magnetic fields, can magnets

make electric fields? - When a magnet is moving through a coil a voltage

is induced at the ends of the coil - This is known as Faraday Induction and is the key

principle for the operation of all motors and

generators

Magneto-Electricity

- The magnetic field moving through the coil can be

either - A magnet that inserted into the coil
- A magnetic field produced by a current in, for

example, another coil - Faraday Induction

Early Generator

- Two sets of coils
- One with a current to make a magnetic field
- The second had a voltage induced
- Device was based on steam engine technology

James Clerk Maxwell

- Born 1831
- Color Vision, 1850
- Saturns Rings, 1855
- Statistical and Molecular Physics, 1859
- A dynamical Theory of the Electric Field, 1864

Amperes Law

The magnetic field around a loop is proportional

to the current going through the loop

Magnetic Field inside a Solenoid

Maxwells Addition

Maxwell added another term to Amperes Law one

that had not been observed

Faraday Induction

- Maxwell did not have the advantage of vector

notation. In describing the magnetic field he

used three functions, F, G, H, for the components

of the field.

Speed of Light

- After 85 pages of derivations, Maxwell was able

to find the equation for an electro-magnetic

wave. - The velocity of the wave was close to the speed

of light

Unification of Electricity and Magnetism

- The connection Faradays Law connected Electric

Field to Magnetic Field - The Unified Theory Maxwell, by adding

displacement current, came up with the single

theory describing electricity and magnetism - The surprise - Light is an electromagnetic wave
- Further examination of the theory lead to the

predictions of Special Relativity

Conclusion

- This is the first of the theoretical unifications
- Unifications are foreshadowed by a connection

in this case the electric and magnetic field - We will see similar connections next time when we

look at - unification of EM with Quantum Mechanics
- unification of Special Relativity with Quantum

Mechanics - unification of the Electric and Weak forces
- unification of Gravity and Quantum Mechanics