LIGHT REVISION Flashcards
What were the TWO rival theories of nature of light?
- The Wave Theory
2. The Corpuscular (Particle Theory)
Explain the Wave Theory by Huygens?
In 1680 Huygens suggested that light was a longitudinal wave capable of propagating through a material called the AETHER which he believed filled all space.
This material medium justified why light can pass through a vacuum despite the fact that it was supposedly a longitudinal wave.
Explain particle theory [Newton]
He proposed that light was shot out from a source like particles and the mass of the source diminished as it released these particles were let out. At this time the diffraction of light had not been observed and newton argued that since light doesn’t diffract it cannot be a wave. He also didn’t know that light travels faster in air than water
Explain wave theory [young]
His theory says that light from two very narrow slits can produce a pattern of bright and dark fringes on a screen. he argued that this was the result of principle of superposition of light acting as waves
However newtons theory lived on since he was a dominant physicist and mathematician
Wave theory [Foucault]
Foucault showed experimentally in 1802 that light travelled faster in air than water contrary to newtons corpuscular theory suggested.
This seemed at the time to be deciding factor the cited the balance in favour of the wave nature of light
Wave-particle duality-Planck and Eisten
Max Planck in 1900 put forward the quantum theory which combined the wave and particle theory in 1905 Eisten showed that the phenonmemnon of photo electric emission cannot be explained by wave theroy but by only particle theroy
