optic wave
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OPTIC WAVE
Hana Fauzyyah Hanifin
OPTIC WAVE
Properties
Huygen’s Priciple
Interference
Dispersion & Refraction
Diffraction SpectrumPolarisation
ResolvingPower
Reflection
Electromagnetic Wave :Propagating perpendicularly in electric and magnetic field
Doesn’t need medium to propagate
1. 2. 5.4.3. 6.
Transverse Wave :The direction of wave’s propagation is perpendicular with the direction of oscillation*Electromagnetic wave is always tranverse wave
1. 2. 5.4.3. 6.
Amplitude :Maximum displacement during vibrationDetermine light intensity (I) / brightness
1. 2. 5.4.3. 6.
I A2
Frequency :Amount of wavelength in a unit time (n/t -> Hz)
Wavelength :Distance between two consecutive trough / crest (x/n -> meter)
Determine the energy carried and the colour
1. 2. 5.4.3. 6.
Speed :Distance covered in a unit time
In free space, c light = c electromagnetic wave = 3.0 * 108 m / s
1. 2. 5.4.3. 6.
c = . f
Wave Optics Energy :
E = wave optics energy
h = planck constant (6.62606957 × 10-34 m2 kg / s)
f = frequency
E ~ f ~ (1/)
1. 2. 5.4.3. 6.
E = h . f
Every point on a wavefront may be considered to be a
source of secondary wavelets (small waves)
Electromagnetic Visible Light
Electromagnetic Visible Light
Interference :When two waves propagates at the same medium they will combine and the amplitude is the resultant of individual amplitude
1 2 43
Young’s Double Slit Experiment :
1 2 43
Young’s Double Slit Experiment :
1 2 43
r1-r2 = d sin
r1-r2 = d ( y / L )
For minima (dark)r1-r2 = ( k - 0.5 )
So, ( k - 0.5 ) = d sin For maxima (bright)r1-r2 = k
So, k = d sin
1 2 43
Pattern of bright and dark fringes will appear if :
-> The sources is coherent (have a constant phase)
-> L is very large compared with d
1 2 43
Diffraction
Diffraction is ...
Spreading of waves through a narrow aperture or bending of waves around an obstacle
1.3.2.
Diffraction
Diffraction Gratings :- The slits are many
- The slits have the same width
- The slits are equally spaced
- Daily application -> CD
k = d sin
1.2.
3.
Diffraction
Diffraction Gratings :
1.2.
3.
Diffraction
Single – Slit Diffraction :
- Fresnel Diffraction -> the L is small so the rays aren’t parallel (wavefront still spherical)
- Fraunhofer Diffraction -> the L is big compared to the d and the rays can be considered parallel
1. 2.3.
Diffraction
Fraunhofer Diffraction :
- The intensity of bright fringe is decrease as the distance to central bright fringe increase
- The light can be considered spread as wide as the central bright fringe
- Central bright fringe always bigger than the slit
1. 2.3.
Diffraction
Fraunhofer Diffraction :
1. 2.3.
Diffraction
Fraunhofer Diffraction :
Minima :
Maxima :
Yk = k (L . /a)
Yk = (k + 0,5) (L . /a)
1. 2.3.
Refraction & Dispersion
Refraction :Bending of waves when the
waves travel in an anglethrough different medium in which the waves propagation velocity is different
1. 2. 3. 4.
Refraction & Dispersion
Refraction :
1. 2. 3. 4.
Refraction & Dispersion
Dispersion :The dependence of the index
index of the refraction upon thewavelength or frequency of thelight
- Polychromatic -> Monochromatic
1. 2. 3. 4.
Refraction & Dispersion
Dispersion :
1. 2. 3. 4.
Po l ar i s a t i o n
Resolving Power
Rayleigh’s Criterion :Sources are said to be just resolved when the central bright fringe of 1 source coincides with the 1st
minimum of the other
Ability of an optical instrumenr to distinguish between objects which are separated by a small angle
min = ( / L)
(x / L)= ( / L)
-> Just Resolved
(x / L) < ( / L)
-> not Resolved
(x / L) > ( / L)
-> Resolved
Reflection
i = r
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