An incident ray from air strikes dolomite (n = 2.0) at an angle of 30 o from normal. Calculate:  refl &  refr

Chapter 19 Diffraction & Interference

List & describe 3 properties of waves

Diffraction The bending of light rays when passing a barrier

Diffraction Named by Francesco Grimaldi by seeing blurred edges of shadows

Isaac Newton Predicted that light moved in the form of particles to explain diffraction

Christiaan Huygens Predicted that light moved in the form of waves to explain diffraction

Thomas Young Proved that light moved in the form of waves by passing light thru a double slit. P 445

Thomas Young The interference pattern caused by diffraction produced dark & light lines

Monochromatic Light Light having only one wavelength

Coherent Waves Waves all in the same phase

Diffraction Interference Light waves d n n L  x x L d =

Diffraction Interference x L d = xd L = Double slit

Calculate wavelength reinforced when waves passing through 2 slits 25  m apart cast bright lines 4.0 cm apart on a screen 2.0 m away

Calculate wavelength reinforced when waves passing through 2 slits 25  m apart cast bright lines that make a 37 o angle from the principle axis

Diffraction Interference d = distance between slits w = slit width xd xw L L = =

Diffraction Interference Light waves d n n L  x  d sin 

Wave Properties Propagation Reflection Refraction Diffraction Interference

Propagation Within a uniformed medium, the generation of waves that move in straight lines called rays

Reflection The bouncing of waves off surfaces or medium boundaries

Refraction The bending of waves when passing from one medium to another

Diffraction The bending of waves when passing around barriers

Interference The superimposing two or more waves passing through the same medium simultaneously

Photoelectric Effect The emission of electrons (e - )from a substance when irradiated

1 st Law of Ph Eff The rate of e - emission is proportional to the intensity of the incident light

2 nd Law of Ph Eff The KE of e - emission is independent of the intensity of the incident light

Photoelectric Effect This led to the discovery that e - in atoms exist in distinct energy levels

Spectroscopy The study of a substance under continuous excitation energy

Energy of a Wave E wave = hf

Energy of Matter E matter = mc 2

Duality of Nature Proposed by Louis de Broglie

Duality of Nature All energy transfer exhibits properties of both waves & particles

Duality Formula = h mv

Calculate the wavelength 2.21 kg of a ball thrown at 20.0 m/s

Calculate the mass of blue light at 442 nm

Calculate the wavelength of a 442 Mg truck moving at 36 km/hr

Calculate the wavelength of a 4.42 x 10 6 Mg train moving at 72 km/hr

The of near IR red light is 663 nm. Calculate: E & m of the light

The of near UV light is 221 nm. Calculate: E & m of the light

Calculate wavelength reinforced when waves passing through 2 slits 25  m apart cast bright lines that make a 53 o angle from the principle axis

Calculate wavelength reinforced when waves passing through a slit 75  m slit cast bright lines that make a 53 o angle from the principle axis

Calculate wavelength reinforced when waves passing through 2 slits 75  m apart cast bright lines 5.0 cm apart on a screen 2.5 m away

Calculate wavelength reinforced when waves passing through a 15  m slit cast bright lines 3.0 cm apart on a screen 2.5 m away

A wavelength 180 nm is reinforced when waves passing through a 15  m slit cast bright lines 3.0 cm apart. What is the screen distance?

A wavelength 18 nm is reinforced when waves passing through a 1.5  m slit cast bright lines 3.0 cm apart. What is the screen distance?

Review

Calculate wavelength reinforced when waves passing through a 25  m slit cast bright lines 5.0 cm apart on a screen 2.5 m away

Calculate the mass & energy of UV light at 221 nm.

Calculate Kinetic energy & wavelength of a 442 g ball going 30.0 m/s

Calculate wavelength reinforced when waves passing through a slit 4.5  m slit cast bright lines that make a 37 o angle from the principle axis