MODULE 7 IQ2

Question 1

newton’s corpuscular theory of light

Answer 1

states that light is made up of tiny particles called corpuscles which travel in straight lines
- corpuscles are so small that they are almost weightless, however they are affected by gravitational attraction and are elastic –> perfect momentum, transfer of energy
“The speed of light increases in water”

Question 2

refraction in newton’s corpusclar theory of light

Answer 2

• each individual corpuscle experiences gravitational attraction force towards other particles
• when light is deep within the medium, it is surrounded by an equal number of particles
• there is an equal force pulling on both sides in the horizontal direction
• however in the vertical direction, water is a denser medium and will have more particles, resulting in a greater attractive force and velocity
  newton predicted that the speed of light increased in denser mediums

Question 3

newton’s wave properties

Answer 3

colour, reflection

Question 4

colour in newton’s wave

Answer 4

wavelengths of light that an object reflects
- different colours of corpsucles are different sizes
- red corpsucles > blue corpsucles
- explains dispersion, as red is deflected less than blue as it has greater mass and inertia

Question 5

what was newtown unable to account for

Answer 5

interference, polarisation, diffraction

Question 6

huygen’s wave theory of light

Answer 6

huygens proposed that every point on a wavefront can be considered a source of secondary wavelets which spread out in a particular direction at the speed of light

Question 7

hugyen’s predictions & proposals

Answer 7

light slows down when it enters water –> this can be generalised for all mediums denser than air
- proposed that light was a longitudinal wave

Question 8

diffraction definition

Answer 8

phenomena of a wave spreading when passed through a slit or an aperture
- best observed when the wavelength is similar to the slit distance

Question 9

superposition definition

Answer 9

phenomena where waves (unlike particles) can occupy the same point in space at the same time and combine
- waves are added together to form a ‘resultant wave’

Question 10

wave interference

Answer 10

constructive interference:
- Δ = d(2)-d(1) = mλ
destructive interference:
- Δ = d(2)-d(1) = (m+1/2)λ

Question 11

what did youngs double slit experiment provide evidence for

Answer 11

huygen’s wave model of light.
demonstrates diffraction & interference

Question 12

youngs double slit experiment process

Answer 12

monochromatic light is sent towards the double slits such that when waves leave our double slits S1 and S2, they are in phase.
- light will diffract across the double slit and propagate to a screen that is placed across the light source and double-slit set up

Question 13

path difference in youngs double slit experiment

Answer 13

integer multiple of a wavelength:
- constructive interference occurs = bright spot (maxima)
integer multiple of a half-wavelength:
- destructive interference occurs = dark spot (minima)

Question 14

when the distance between the double slits increase…

Answer 14

… the number of bright bands we see also increases