Theory of Light Flashcards
Speed of light in a vacuum
C = 3.00x10^8 m/s
Speed of light in a vacuum
C = 3.00x10^8 m/s
study of light
Optics
Two Theories of Light
Wave and Particle Theory
Theory that says light is composed of subatomic particles (quanta) called photons
Particle Theory
Theory that says light is a form of radiant energy that travels wave-like from one point to another.
Wave Theory
discrete packets of energy that carry momentum, have no mass and travel at the speed of light
Photons
Main source of natural light on Earth
Sun
Cornea absorbs below?
360nm
rods and cones cannot detect less than?
360nm
infants can detect up to?
300nm
____ have light receptors that affect morphogenesis
Plants
Contains both electric and magnetic fields that change or oscillate.
Electromagnetic Radiation
True or False: Both E and B are perpendicular to the propagation of the wave
True
Number of crests/troughs that pass a given point within one second; expressed as Hertz (Hz)
Frequency
The distance between two crests.
Wavelength
The amount of kinetic energy
Energy
Measurements of:
centimeter (cm)
angstrom (A na may dot sa taas)
nanometer (nm)
micrometer (mm)
cm: 10^-2
A na may dot sa taas: 10^-10
nm: 10^-9
mm: 10^-6
A and B in electromagnetic radiation
A: wave fronts
B: wave normal
represents the direction of propagation of light energy.
Light ray
Characteristics of Isotropic Minerals in Waves
(isometric minerals; mineralods)
Light rays are parallel to wave normal
Shows same velocity of light in all directions
Bonds are the same in all directions
Characteristics of Anisotropic Minerals in Waves
(tetragonal, hexagonal, orthorhombic, monoclinic and triclinic minerals)
Light rays are not parallel to wave normal
Shows different velocity of light in all directions
Bonds are not the same in all directions
The 7 Primitive Crystal Systems
Isometric
Tetragonal
Orthorhombic
Hexagonal
Triclinic
Monoclinic
Rhombohedral
The distance that one wave lags behind the other (measured in nm)
Retardation (triangle symbol)
where i is an integer, then the two waves are said to be in phase
constructive interference
two waves are said to be out of phase
destructive interference
consists of just one wavelength
Monochromatic light
several wavelengths, but perceived as one color
Polychromatic light
When a light wave encounters an objective, it is either?
transmitted, reflected, absorbed, refracted, polarized, diffracted, or scattered
Behavior of light also depends on the composition of the ___ and ____ of the light.
object/medium and wavelength
the measure of the amount of light that can successfully pass through a medium.
Transmission
The measure of the amount of light energy that materials can absorb, reflect, and scatter.
Transmittance
When incident light (incoming light) hits an object and bounces off
Reflection
occurs when photons from incident light hit atoms and molecules and cause them to vibrate
Absorption
The bending and spreading of waves around an obstacle
Diffraction
occurs when light bounces off an object in a variety of directions
Scattering
light waves change direction as they pass from medium to another
Refraction
depicts the limiting of the direction of their oscillations
Polarization
Is light fast or slowed when it enters a medium?
Slowed
A measure of how effective a material is in bending light coming from a vacuum
Index of Refraction
Most minerals have indices of refraction that fall in the range of ___ to about ___
1.4 to 2.0
Law that tells that light is refracted towards the normal to the boundary upon entering a material with higher n and is refracted away from the normal upon entering a material with lower n.
Snell’s Law
Ordinary light vibrated in all directions mean?
Unpolarized
in optical mineralogy and petrography, we need to use _____
polarized light
Are all crystalline materials birefringent
No
different indices of refraction associated with different crystallographic directions
birefringent
visualize aspects of the samples through light rotated by the sample and then able to pass through the analyzer
Polarization of light
