An incident ray from air strikes dolomite (n = 2.0) at an angle of 30o from normal.
Calculate: refl & refr
Chapter 19Diffraction & 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
Lightwaves
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 37o angle from the principle axis
Diffraction Interference
d = distance between slits
w = slit width
xd xw L L
= =
Diffraction Interference
Lightwaves
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
1st Law of Ph Eff•The rate of e- emission
is proportional to the intensity of the incident
light
2nd 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
Ewave = hf
Energy of Matter
Ematter = mc2
Duality of Nature
Proposed by Louis de Broglie
Duality of NatureAll energy transfer exhibits properties of both waves &
particles
Duality Formula
= hmv
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 106 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 53o angle from the principle axis
Calculate wavelength reinforced when waves
passing through a slit 75 m slit cast bright lines
that make a 53o 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?
Calculate wavelength reinforced when waves
passing through a 25 m slit cast bright lines 5.0
cm apart on a screen2.5 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 37o angle from the principle axis