Corpurscular Theroy Flashcards
What is Newtons Corpuscular theory ?
-light ray as a stream of particles called Corpuscles
-based on the laws of motion of particles : particles travel in a straight line unless acted on by a force
According to Newton, what happens in Reflection ?
-When light reflects from a surface ; these corpuscles bounce off without any change in velocity.
What happens to speed and energy in Newtons theory
-Speed remains constant
-Energy is conserved
According to Newton, what happens in Refraction?
-When a light ray is refracted on passing from air into a transparent substance,
Newton said the corpuscles are attracted into the substance so they travel faster
in the substance than in air.
-Velocity along the boundary is the same
What was wrong with Newtons theory of light
According to this Newton’s theory and explanation, speed of light increases in a dense medium.
At that time the speed was not measured and no method was available, to prove this idea.
What was Hugens wave theory in 1678
-light beam is not made of corpuscles, but they are waves
-assumed light waves travel slower in a transparent substance than in air.
Why was Huygen’s theory rejected and why was NEWTONS theory PREFFERED?!
-was not possible to measure the speed of light in air or in a transparent substance at that time so there was no experimental evidence showing whether light travels faster or slower in a transparent substance than in air.
-Newton had a much stronger scientific reputation than Huygens so most scientists thought Newton’s theory was correct.
-This wave theory could not explain polarisation, because Huygens assumed light as longitudinal wave.
