5.4 Flashcards
what was the idea about the nature of light pre Youngs double slit
newton considered that light was composed of tiny particle and could explainnreflection and reflation with his theory
Huygens thought they were waves and could also prove reflection and refraction
how can we observe interference of light
illuminate two closely spaced parallel slits
what do the two slits act as
coherent sources of waves meaning they emit light waves with a constant phase difference and the same frequency
what happens if the single slit is too wide
pattern is displaced slightly to the adjacent parts of th single slit
as a result the dark fringes of the double slit pattern become narrower and contrast between fringes is lost
why must the arrangement of the fringes using a laser be shown on a screen
laser will damage the retina if it enters the eye
why are the fringes formed
due to interference of light from the two slits
what is the interference where a bright fringe is formed
the light from one slit reinforces the light from the other slit and they arrive in phase
what is the interface where a dark fringe is formed
the light from one slit cancels the light from the other slit
they arrive 180 degrees out of phase
fringe seperation equation
w = lambda x d /s
d= distance from slit screen
s= slit spacing
when do the fringes become more widely spread
if distance from screen to slit is increased
if wavelength is increased
if slit spacing is decreased
reinforcement at part p
s1p -s2p =m lambda
cancellation at point p
s1p -s2p = (m+1/2)lambda
