Fundamentals of Light Flashcards
You will understand sources of light and how light illuminates the universe around us. You will be able to describe the wave nature of light and some phenomena that reveal this nature
a stream of fast-moving, unimaginably tiny particles
corpuscles
Light is represented as a ray that travels in a straight path.
The direction of which can be changed only by placing an obstruction in the path
ray model of light
major source of light
Sun
An object that emits light
Luminous Source
An object that becomes visible as a result of the light reflecting off it.
Illuminated Source
Media that do not transmit light but reflect some light
Opaque Media
Media that transmit light, such as air and glass,
Transparent Media
Media that transmit light but do not permit objects to be seen clearly
Translucent media
They not only transmit light, but they also can reflect a fraction of the light.
Transparent or translucent media
The rate at which light energy is emitted from a luminous source.
luminous flux, P
The illumination of a surface, or the rate at which light strikes the surface
Illuminance, E
Illuminance is measured in?
lux, lx
a measure of luminous intensity
Candela
luminous intensity
luminous flux divided by 4pi.
Point Source Illuminance
Lux [lx] = luminous flux [lm] / area [m2]
If r is constant, then E is directly proportional to P
When P increases, E increases
When P decreases, E decreases
If P is constant, then E is
inversely proportional to r^2
When r 2 increases, E decreases.
When r 2 decreases, E increases.
He was the first to determine that light
does travel with a measurable speed.
Ole Roemer
known value of the diameter of Earth’s orbit
(2.9*10^11 m)
speed of light in a vacuum
c = 299,792,458 m/s.
a light-year
9.46x10^12 km
the bending of light around a barrier
diffraction
the ordered arrangement of colors
spectrum
primary colors
red, green, and blue
secondary colors
yellow, cyan, and magenta
Two colors of light that can be combined to
make white light.
Complementary colors
a molecule that absorbs certain wavelengths of light and transmits or reflects others
Dye
A pigment that absorbs only the primary color and reflects two from white light is called
primary pigment
A pigment that
absorbs two primary colors and reflects one color is called
secondary pigment
the colors of primary pigments
Yellow, cyan, and magenta
The colors of secondary pigments
red (which absorbs green
and blue light), green (which absorbs red and blue light), and blue (which absorbs red and green light)
the production of light in a single plane of oscillation
Polarization
They contain long molecules in which electrons can oscillate, or move back and forth.
all in the same direction.
Polarizing media
The direction
of a polarizing medium perpendicular to the long molecules is called
polarizing axis
The law that explains the reduction of light intensity as it passes through a second polarizing filter is called
Malus’s law
A positive change in wavelength means
the light is red-shifted
A negative change in wavelength means
the light is blue-shifted
Used to measure the Doppler shift of these wavelengths
spectrometer
In 1929, he suggested that the universe is expanding
Edwin Hubble
In what year did Edwin Hubble suggested that the universe is expanding?
1929
