Light and Optical Systems - Topics 1-3

Question 1

Light

Answer 1

Energy that you can see

Question 2

Natural light source

Answer 2

A non human made source of light such as the sun or fire

Question 3

Radiates

Answer 3

light spreads out

Question 4

Radiation

Answer 4

The transfer of radiant energy, such as light

Question 5

Radiant energy

Answer 5

Energy transferred as waves or rays in all directions

Question 6

Artificial light source

Answer 6

A human made source of light. Example: light bulb

Question 7

Basic Principles of Light

Answer 7

1. Light is a form of energy

Question 8

Light can be transformed into what three kinds of energy?

Answer 8

Thermal, electrical, chemical

Question 9

Incandescent

Answer 9

Visible light is emitted by a hot object. Examples: candle flames, light bulbs (electricity heats a metal wire filament in the bulb, it becomes so hot that it glows)

Question 10

Fluorescent

Answer 10

High energy invisible ultraviolet light is absorbed by the particles of an object. Example light bulbs - electricity causes mercury vapor to give off ultraviolet radiation., which is absorbed by phosphor particles to create visible light.

Question 11

Light Emitting Diodes

Answer 11

LED - emits light when a voltage is applied to it. (electrical energy becomes light energy)

Question 12

Phosphorescence

Answer 12

Emission of light following exposure to and removal of a source of radiation

Question 13

Chemiluminescence

Answer 13

Emission of light resulting from chemical action and NOT involving heat. Example: glow sticks

Question 14

Bioluminescent

Answer 14

Emission of light produced by chemical reactions inside the bodies of living things. Examples: some fish, fireflies

Question 15

Cost of lighting (in 2001)

Answer 15

Cost = kWh X price (cents/kWh)

Question 16

Ray model of light

Answer 16

A model of light based on the observation that light travels in a straight line

Question 17

Ray

Answer 17

straight line that represents the path of a beam of light

Question 18

Ray diagram

Answer 18

A representation of the path of light by using a straight line with an arrow

Question 19

Transparent

Answer 19

Allows light to pass through in a straight line

Question 20

Translucent

Answer 20

Allows some light to pass through and then is scattered

Question 21

Opaque

Answer 21

Does not allow light to pass through, bounces back

Question 22

Reflection

Answer 22

Light strikes a surface and bounces back off that surface

Question 23

Incident Ray

Answer 23

the ray that comes from a light source and strikes the surface

Question 24

Reflected Ray

Answer 24

The ray that bounces off the surface

Question 25

Normal line

Answer 25

A reference line draw perpendicular to a reflecting surface at the point where the incident ray strikes the surface

Question 26

Angle of incidence

Answer 26

the angle between the incident ray and the normal line

Question 27

Angle of reflection

Answer 27

the angle between the normal line and the reflected ray