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111 Cards in this Set
- Front
- Back
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define light.
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a form of energy that can be detected by the human eye
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what is the only way we know light exists ?
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we see it and the effects on matter
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when light strikes a material, these one of these 3 things will occur,
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light would be
reflected, transmitted, or absorbed |
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light energy from different sources can be classified as
(2 things) |
natural and artificial
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objects that emit(give off) energy in the form of light are said to be _________
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luminous
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objects that do not emit light but only reflects light from other sources are said to be _______
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nonluminous
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is the moon luminous or nonluminous?
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nonluminous
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what are common forms of input energy?
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chemical energy, thermal energy, electrical energy, nuclear energy
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what is input energy?
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input energy transforms into light energy to produce light
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describe "incandescence"
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the process of emitting light because of high temperatres
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what is an example of incandescent light sources
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kerosane lamp
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the hotter the metal is heated the different colours it will turn.. what ranges of colours are there?
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dull red>yellow>white>blue-white
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define phosphorescence
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the process of emitting light for a short time after recieving energy from another source
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give an example of a phosphorescence light source
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glow-in-the-dark items
ex. the printed luminous dials on some watches and clocks |
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define electric discharge
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the process of emitting lgiht because of electricity passing through a gas
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what is a natural form of electric discharge?
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lightning
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what is a light source of electric discharge?
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neon light
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define fluorescence
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the process of emitting light while receiving energy from another source
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which two sources of light does the fluorescence light use?
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electric discharge and phosphorescence
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which will produce more heat, fluorescent or incandescent light bulbs?
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incandescent
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define chemiluminescence
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the process of changing chemical energy into light energy with little or no change in temperature
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name an example of chemiluminescence
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a glowstick (you change the chemical energy into light energy by cracking it... this has no change in temperature)
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define bioluminescence
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the chemical reaction similar to chemiluminescence that living materials use to be luminous
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give examples of living objects that use bioluminescence
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fish, squid, bacteria, fungi, fireflies, and glow-worms
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define transparency
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it is the measure of how much light can pass though a material.
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what are the three transparency groups materials are classified as?
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transparent, translucent, and opaque
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what happens to light if an object is transparent?
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light can easily pass through and it is see through/ clear
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what happens to light if an object is translucent?
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light is transmitted which means some is able to pass though and the rest is reflected
(examples: frosted glass, clouds , fingernails) |
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what happens to light if an object is opaque?
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no light is allowed to pass through. the object is not see through at all
(example: milk, wood, stone, bricks...) |
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water actually absorbs and reflects light slightly. what happens when you have small, larger, and very large amounts?
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small amount of water- transparent
larger amount of water- translucent very large amounts of water- opaque |
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absorbed light energy is converted in to __________ energy
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thermal
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dull textured materials and dark coloured materials will always ____more light
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absorb
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light usually and normally travels in _______lines
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staright
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define the visible spectrum
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a band of colors you can see in the rainbow
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what are the spectural colours?
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red, orange, yellow, green, blue, and violet
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which scientist discovered that white light actually contains the spectral colours
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sir isaac newton
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how did sir Isaac Newton test his theory that white light contained the spectral colours ?
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he shone a beam of sunlgiht through a triangular glass prism
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which colour bends/ changes direction/ slows down the most?
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violet
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when the colours of light travels at different speeds, what happens to each colour?
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each colour slightly changes direction
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when an opaque object is white, which colours of the spectral colours are reflected?
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all of the colours
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when an opaque object is black, which colours of the spectral colours are reflected?
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none, they are all absorbed
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what is the electromagnetic spectrum?
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the entire range of radiant energies
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what is the "speed of light" or the speed that light other parts of the electromagnetic spetrum travel at?
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300 000km/a second
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How long does it take light to travel from the moon to us?
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1.3 seconds
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How long does it take light to travel from the sun to us?
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8 minutes
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what happens when light is refracted?
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light is bent or changes direction
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what does transmit mean?
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passes through
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when electromagnetic waves travel in a vacuum, what does it mean?
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vacuum is in the air
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Are the speed of light and other parts of the electromagnetic spectrum the same?
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yes
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What is a wave?
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it is the result of a vibration that transfers energy from one location to another
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what causes a wave and is a regular repeated motion
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vibration
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Electromagnetic waves transfer electromagnetic energy through _________and__________
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space and transparent materials
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the name of the highest point above the equilibrium is...
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the crest
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the name of the lowest point below the equilibrium is...
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the trough
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the maximum distance between the crest and equilibrium or the trough and the equilibrium is called...
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the amplitude
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what is the equilibrium?
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it is the resting position or the place if there was no wave.
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what does the amplitude determine?
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the amplitude determines the amount of energy being transfered
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the higher the wave, the ____ energy it has
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more
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what is the wavelength?
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it is the distance between the two adjacent crests or two adjacent troughs
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what is the frequency of a wave?
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it is the number of cycles in a period time
cycles/sec |
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what is the measurement of frequency measured in?
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hertz (Hz)
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How many Hz/ hertz is in one kHz/ kilohertz?
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1000 Hz
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How many Hz/hertz is in one MHz/ megahertz?
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1 000 000 Hz
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How many Hz/Hertz is in one GHz/ gigahertz?
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1 000 000 000 Hz
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What happens to the wavelengths as the waves in the electromagnetic spectrum get stronger?
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the wavelengths decrease
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What is the relationship between wavelength, frequency, and energy?
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short wavelength
high frequency high energy ___________________ long wavelength low frequency low energy |
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what are all the different types of classification for waves in the electromagnetic spectrum?
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staring from least to most powerful)
radio, microwaves, infrared radiation(IR), visible light, ultraviolet radiation (UV), x-rays, gamma rays |
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Name some uses of a radio wave
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- ship and boat communication
- AM and RM radio stations - cellular telephone - television |
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Name some uses of microwaves
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- microwave ovens
- communication |
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Name some uses of visible light
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- artificial light
- lasers |
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Name some uses of ultraviolet radiation (UV)
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- suntanning
- "black lights" in shows |
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Name some uses of x-rays
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- x-ray photographs of parts of the human body (bones)
- measurements of thickness in manufacturing |
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Name some uses of gamma rays
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- study of what makes up matter
- study of unusual events in distant galaxies - nuclear plants |
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What is the frequency of low radio waves in Hz?
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3 000 000 000 Hz ( 3 million)
-or- 3 GHz |
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What is the frequency of high frequency of gamma rays in Hz?
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30 000 000 000 000 000 000 Hz
-or- 300 GHz |
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what would you have to do to increase the amplitude of the wave?
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use more power to let more energy travel through
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what is the most common luminous abject and the most important source of light?
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the Sun
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When is light produced by luminous objects
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when some of the luminous object's energy is transformed into light energy
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When are shadows produced?
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when light shines on a opaque object because light cannot pass through the object
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What is more efficient? light sources that produce a lot of heat energy or light sources that produce little heat energy
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light that produces little heat energy
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What are the invisible parts of the electromagnetic spectrum?
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longer wavelengths=radio waves, microwaves, infrared radiation
_____________ shorter wavelengths=ultraviolet, radiation, X-rays, gamma rays |
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What is an optical device?
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a device that produces an image of a object
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What is the ray of light that travels towards a reflecting surface called?
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the incident ray
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what is the normal?
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the line drawn 90 degrees from the surface of the optical device
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what is the angle of incidence?
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the angle of incidence is the angle between the incident ray and the normal
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what is a ray of light that bounces off a reflecting surface called?
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the reflected ray
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what is the angle of reflection?
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it is the angle between the reflected ray and the normal
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What are flat mirrors called?
_________ |
plane mirrors
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When light hits the surface of a plane mirror, is the reflected light rays predictable?
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yes
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When light hits the surface of a uneven/ irregular surface, is the reflected light rays predictable?
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no, the reflected light rays will bounce everywhere
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What is specular reflection?
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it is when light reflects off a smooth, shiny surface
eg. mirrors, shiny metals, still water |
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What are the two laws of reflection?
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-the angle of incidence equals to the angle of reflection
-the incident ray, normal, and the reflected ray all lie in the same side of the plane |
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what is a diffuse reflection?
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when light hits an irregular surface and the reflected light scatters in many directions
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diffuse lights can be easier to see on the eye, why?
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bumpy surfaces cause diffuse reflection which is easier for the eye
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What happens when you have indirect lighting?
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The light bulbs cannot be see and the light reflects off the walls or ceiling before it reaches your eye
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when you look in the mirror, images look as if it is ____ the mirror
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inside
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What is the main/ biggest difference between a real and a virtual image?
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a real image can be placed on a screen
a virtual image cannot be placed on a screen |
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what is the only way you can see a virtual image?
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by looking at or through an optical device
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what are the four characteristics to describe images
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size, attitude, location, and type
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size is one of the four characteristics to describe an image, what does that mean?
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size -
- smaller than the object viewed - larger than the object view - same size as the object viewed |
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attitude is one of the four characteristics to describe an image, what does it mean?
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attitude-
- whether the image is upright (right side up) or inverted (upside down) |
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location is one of the four characteristics to describe an image, what does it mean?
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location-
- several choices ] - examples: on the side of the lens opposite the object, closer to the optical device than to the object |
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type is one of the four characteristics to describe an image, what does it mean?
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type-
- real image(can be placed on a screen) -virtual image(can be seen only by looking at or through an optical device)<- virtual image |
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What are the types of curved mirrors?
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concave and convex
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How does a concave mirror look like and where is the reflective side ?
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the reflective side curves in
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How does a convex look like and where is the reflective side?
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the reflective side curves outwards
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what is the principal axis?
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a line through the center of the mirror that includes the principal focus
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What is the principal focus?
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the position where reflected parallel light rays come together
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What is the focal length?
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the distance from the principal focus to the middle of the mirror
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What does the concave mirror do to the parallel light rays?
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it focuses it
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What does the convex do to the parallel light rays ?
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it spreads it out (opposite of what happens to concave mirrors)
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