Chapter 7: Understanding Light

Question 1

Give two examples of natural light sources

Give two examples of artificial light sources

Answer 1

Fire, sun, fireflies, jellyfish

Lightbulbs, glow in the dark watches

Question 2

What is radiant energy?

Answer 2

Light that spreads out or radiates from a natural sources

Question 3

What is it called when light bends?

Answer 3

Refraction

Question 4

What is the light that bounces of an object called?

Answer 4

the reflected ray

Question 5

What is the normal?

Answer 5

The imaginary line perpendicular to a surface

Question 6

Give an example of radiant energy

Answer 6

The energy given of from a light bulb

Question 7

Transparent
Translucent
Opaque

Answer 7

See through
Mostly see through
Can’t see through

Question 8

Incandescent sources produce a lot of_____

Answer 8

heat

95% of the energy given off from an incandescent source is thermal. Its like having a mini heater in your room

Question 9

Luminous

Answer 9

Glowing, gives off it’s own light

Question 10

What equals the angle of reflection?

Answer 10

The angle of incidence

Question 11

Why should you wear white when its sunny?

Answer 11

Because black absorbs heat meanwhile white reflects it

Question 12

Give three examples of forms of radiant energy

Answer 12

Thermal energy (heat)
Chemical energy (food)
Electrical (electricity)

Question 13

What word can we use to describe the brightness of light?

Answer 13

Intensity

Question 14

Where does the suns energy come from?

Answer 14

Nuclear Fusion

Question 15

Energy transformation for incandescent source

Answer 15

Electrical energy -) Thermal energy -) Visible light energy

Question 16

Energy transformation for fluorescent source

Answer 16

Electrical energy -) Energy absorbed by mercury particles -) Ultraviolet energy -) energy absorbed by phosphor particles -) Visible light energy

Question 17

Describe how a phosphorescent source works

Answer 17

Stores energy particles for awhile and releases this energy as visible light. This is how we get the glow in the dark radiation.

Question 18

Chemiluminescent

Answer 18

Light given off as a by product of a chemical reaction. Example glow stick

Question 19

What are the two basic properties of light?

How does light travel?

Answer 19

Light is a form of energy
Light always travels in straight line
(Light is travels in waves)

Question 20

What is reflection?

Answer 20

When light bounces of a surface. This is necessary in order to see the object. The rest of the light is abdsorbed

Question 21

What is a light ray that strikes a surface called?

Answer 21

Incident Ray

Question 22

When the incident ray is reflected what is it called?

Answer 22

The reflected ray

Question 23

What are the laws of reflection?

Answer 23

1. The angle of reflection is equal to the angle of incidence
2. The incident ray, the normal and the reflected ray are all in the same plane.

Question 24

What is refraction?

Answer 24

When light moves from one medium to another

Question 25

Why does light bend?

Answer 25

Because it changes speed when it moves between materials with different densities.

Question 26

Statement, VERY IMPORTANT!!!!!! MEMORIZE!!!!!!!!!!!!!!!!!!!!!

Answer 26

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.

Question 27

What is the angle of refraction? | What happens when angle of incidence increases?

Answer 27

When light BENDS from moving from one direction to another. The angle of incidence increases as well BUT no necessarily by the same amount.

Question 28

How does a mirage work?

Answer 28

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

Question 29

What is light?

Answer 29

Light is a form of energy