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