Chapter 7: Understanding Light Flashcards
Give two examples of natural light sources
Give two examples of artificial light sources
Fire, sun, fireflies, jellyfish
Lightbulbs, glow in the dark watches
What is radiant energy?
Light that spreads out or radiates from a natural sources
What is it called when light bends?
Refraction
What is the light that bounces of an object called?
the reflected ray
What is the normal?
The imaginary line perpendicular to a surface
Give an example of radiant energy
The energy given of from a light bulb
Transparent
Translucent
Opaque
See through
Mostly see through
Can’t see through
Incandescent sources produce a lot of_____
heat
95% of the energy given off from an incandescent source is thermal. Its like having a mini heater in your room
Luminous
Glowing, gives off it’s own light
What equals the angle of reflection?
The angle of incidence
Why should you wear white when its sunny?
Because black absorbs heat meanwhile white reflects it
Give three examples of forms of radiant energy
Thermal energy (heat) Chemical energy (food) Electrical (electricity)
What word can we use to describe the brightness of light?
Intensity
Where does the suns energy come from?
Nuclear Fusion
Energy transformation for incandescent source
Electrical energy -) Thermal energy -) Visible light energy
Energy transformation for fluorescent source
Electrical energy -) Energy absorbed by mercury particles -) Ultraviolet energy -) energy absorbed by phosphor particles -) Visible light energy
Describe how a phosphorescent source works
Stores energy particles for awhile and releases this energy as visible light. This is how we get the glow in the dark radiation.
Chemiluminescent
Light given off as a by product of a chemical reaction. Example glow stick
What are the two basic properties of light?
How does light travel?
Light is a form of energy
Light always travels in straight line
(Light is travels in waves)
What is reflection?
When light bounces of a surface. This is necessary in order to see the object. The rest of the light is abdsorbed
What is a light ray that strikes a surface called?
Incident Ray
When the incident ray is reflected what is it called?
The reflected ray
What are the laws of reflection?
- The angle of reflection is equal to the angle of incidence
- The incident ray, the normal and the reflected ray are all in the same plane.
What is refraction?
When light moves from one medium to another
Why does light bend?
Because it changes speed when it moves between materials with different densities.
Statement, VERY IMPORTANT!!!!!!
MEMORIZE!!!!!!!!!!!!!!!!!!!!!
When light travels from one medium to a denser one, it will bend toward the normal. When light moves away from the denser medium it bends away from the normal.
What is the angle of refraction?
What happens when angle of incidence increases?
When light BENDS from moving from one direction to another.
The angle of incidence increases as well BUT no necessarily by the same amount.
How does a mirage work?
A mirage is when the air near the ground warms up, light from objects at a distance is refracted in a curved path. This causes the illusion of a water surface which is really the image of the sky refracted be warm air near the ground
What is light?
Light is a form of energy
