Summary
Until the work of Maxwell light appeared to have no connection to electricity or magnetism
- Travels at speed c about 300,000,000 m/s (known before Maxwell)
Maxwell’s (1873) theory of electricity & magnetism
- Four equations that completely determine all of E & M You are NOT responsible for the equations!
- Newton’s and Maxwell’s equations describe all “classical physics”
Maxwell’s equations lead to electromagnetic waves
- Electric and magnetic forces are NOT instantaneous “action at a distance forces”
- Move as electromagnetic fields that travel at a velocity determined from E&M constants = c = speed of light !
Light is an electromagnetic wave!
- What is a wave? (Next lecture) What is waving?
- How can light go through free space (vacuum)?
- What does light travel through?
- The “Ether” ?? -- a massless substance invented to carry light??