Sources of Light (slide 3)

Question 1

Light enters our eyes from

Answer 1

ALL objects

Question 2

Two types of objects

Answer 2

luminous and non luminous

Question 3

luminous

Answer 3

produces it’s own light

Question 4

non luminous

Answer 4

does not produce it’s own light (can only be seen by reflected light)

Question 5

Technologies can produce light by

Answer 5

converting other forms of
energy into forms of light

Question 6

There are many forms of energy that is converted

Answer 6

Chemical energy

Electrical energy

Nuclear energy

Thermal energy

Question 7

common sources of light include

Answer 7

incandesecense
light from electric discarge
luminessceneces
fluoressense
phophorescence
chemilumuminscene

light emitting (diod)

Question 8

Incandescence

Answer 8

The production of light as a result of high temperature

Question 9

Incandescence is

Answer 9

Inefficient (more heat) (10% of it is light)
Heat 🡪 light

Question 10

Incandescent light bulb

Answer 10

Electrical energy 🡪 heat + light (light bulb)

Question 11

Fuel-burning technologies

Answer 11

Chemical energy 🡪 heat + light (lighter)

Question 12

Light from Electric Discharge

Answer 12

The process of producing light by the build up and quick transfer of
electrons between two objects

The process of producing light by an electric current flowing through gas

Question 13

Lightning

Answer 13

massive charge build up of charge-charge will want to lose charge to (discarge)

Question 14

Luminescence

Answer 14

Light generated without heating the object

Question 15

The energy used to excite the atoms comes from a variety of sources

Answer 15

(Luminescence)

Question 16

Fluorescence

Answer 16

Visible light that is emitted immediately after exposure to
ultraviolet light
Efficient

Question 17

Phosphorescence

Answer 17

Visible light that is emitted gradually after exposure to ultraviolet
light
UV radiation 🡪 light
Re emit it over a long period of time

Question 18

Chemiluminescence

Answer 18

Light that is generated by the energy released in a chemical reaction without a
rise in temperature

Question 19

Chemical energy 🡪 light (glow stick)

Answer 19

Chemiluminescence

Question 20

break the glow stick you break the a stick inside holding chemical hydrogen peroxide

Answer 20

causes light

Question 21

Bioluminescence

Answer 21

Light is produced from a chemical reaction in living organisms

Chemical energy 🡪 light

Question 22

Bioluminescence (examples)

Answer 22

Firefly and jelly fish

Question 23

Triboluminescence

Answer 23

Light is produced when certain crystals are scratched, crushed, or
from vibration
MECHANICAL ENERGY

Question 24

Mechanical energy 🡪 light

Answer 24

Triboluminescence

Question 25

Light emitting DIOD

Answer 25

When electric current flowing through semi conducter is produced
Electtric energy-light

Question 26

Describe the difference between luminous objects and non-luminous objects.

Answer 26

Luminous objects produce their own light.
Non-luminous objects do not produce their own light – only seen because they reflect
light

Question 27

Describe how light is produced through incandescence. Provide one (1) example.

Answer 27

Light is produced through incandescence when an object is heated to high
temperatures (light produced with heat).
Fire is a source of incandescent light

Question 28

Describe how light is produced through luminescence. Provide two (2) examples.

Answer 28

Light is produced through luminescence when an object converts energies other than
heat into light (light produced with little or no heat).
Chemiluminescence (glow sticks) produce light through chemicals reacting.
Fluorescence (light bulbs) produce energy through charging fluorescent particles
(which produces visible light) using UV light.

Question 29

What is the main difference between fluorescence and phosphorescence?

Answer 29

Both fluorescence and phosphorescence absorb UV radiation to charge it’s particles
before visible light is emitted. The difference is that fluorescence releases all of the
energy as visible light immediately while phosphorescence gradually releases the
energy as visible over longer periods of time.

Question 30

State two (2) reasons how/why living organisms might use bioluminescence.

Answer 30

Defensive Adaptation: confuse/evade predators
Offensive Adaptation: lure prey
Attraction: attract mates

Question 31

6. Explain why homeowners should switch from incandescent light bulbs to fluorescent or LED
   light bulbs.

Answer 31

Fluorescent (and LED) light bulbs produce the same amount of light as incandescent
light bulbs, but use less energy to do so and has a longer lifetime than incandescent
bulbs.