nature and sources of light

Question 1

what are the 2 types of light?

Answer 1

natural

artificial

Question 2

light

Answer 2

the only form of energy that can travel like a wave through empty space and through some materials

Question 3

what kind of wave does light behave like?

Answer 3

electromagnetic

Question 4

can you see electromagnetic waves?

Answer 4

no, they are invisible

Question 5

electromagnetic waves can travel through a ______ at the ______

Answer 5

vacuum / speed of light

Question 6

what is the speed of light?

Answer 6

3 x 10 to the power of eight m/s

Question 7

wavelength

Answer 7

distance from the peak of one wave to the peak of the next wave

Question 8

frequency

Answer 8

number of complete wavelengths that pass a given point in one second

Question 9

electromagnetic spectrum

Answer 9

diagram that illustrates the arrangement of electronic waves according to wavelength or frequency

Question 10

low energy= ____ wavelength

Answer 10

long

Question 11

high energy= ____ wavelength

Answer 11

short

Question 12

visible light

Answer 12

any electromagnetic wave that the human eye can see

Question 13

visible spectrum

Answer 13

continuous sequence of different colours together form visible white light

Question 14

luminous source of light

Answer 14

gives off its own natural light

Question 15

artificial source of light

Answer 15

production of light by converting external energy forms (chemical, electrical, thermal)

Question 16

non-luminous source of light

Answer 16

does not give off its own light, may appear bright because of reflection from a luminous object

Question 17

what are 3 types of light emission?

Answer 17

from the sun
from incandescence
from electric discharge

Question 18

light from the sun:

fusion reaction: ______ atoms in the sun’s core collide and sometimes ___________

Answer 18

hydrogen / combine or fuse to form

Question 19

light from the sun:

tremendous amounts of ______ is released

Answer 19

energy

Question 20

light from the sun:

energy transmitted to the bases on _________

Answer 20

outer layers of sun

Question 21

light from the sun:

excited atoms release ___________

Answer 21

excess energy

Question 22

light from the sun:

_____ is emitted

Answer 22

light

Question 23

light from incandescence

Answer 23

a light emitted by a very hot object

Question 24

incandescent bulbs are very inefficient at producing light. how much energy used becomes light versus how much energy is lost as heat?

Answer 24

5% light / 95% heat

Question 25

step one of incandescent lighting | __________ runs through Tungsten wire

Answer 25

electrical current

Question 26

step two of incandescent lighting | Tungsten wire heats to what temperature?

Answer 26

3000 degrees Celsius

Question 27

step three of incandescent lighting | ____ excites atoms

Answer 27

heat

Question 28

step four of incandescent lighting | atoms release light-- ______ glows

Answer 28

filament

Question 29

light from incandescence | what is the chemical formula for: chemical energy --> heat + light

Answer 29

CnHn + O2 --> CO2 + H2O + energy

Question 30

what is energy made up of (in the chemical formula for incandescence)?

Answer 30

heat, light

Question 31

chemical discharge

Answer 31

electric current passes through a gas or vapour; excites the atom and energy is released; light is emitted

Question 32

step one of chemical discharge | electron receives _______

Answer 32

energy

Question 33

step two of chemical discharge | electron gets ______

Answer 33

excited

Question 34

step three of chemical discharge | light and heat released as _______________

Answer 34

electron loses energy

Question 35

neon lights-- red

Answer 35

neon

Question 36

neon lights-- greenish blue

Answer 36

argon and mercury

Question 37

neon lights-- pale violet

Answer 37

krypton

Question 38

neon lights-- pink

Answer 38

helium

Question 39

fluorescence

Answer 39

light that is emitted when energy of ultraviolet light is absorbed by a substance and invisible light is converted to visible light

Question 40

4 benefits to fluorescent bulbs

Answer 40

last longer use less electrical energy 4x more efficient than incandescent light bulbs environmentally friendly

Question 41

2 uses to fluorescent bulbs

Answer 41

forensic investigators can detect fluorescent biological fluids dentists can detect unhealthy tissue as they appear in darks spots

Question 42

phosphorescence

Answer 42

light emitted due to exposure of UV light to the source and that continues to be emitted long after the UV light is taken away

Question 43

chemiluminescence

Answer 43

light that is generated by a chemical reaction without a rise in temperature

Question 44

bioluminescence

Answer 44

light that is produced by a biochemical reaction in a living organism

Question 45

wavelengths of light emitted from hot object

Answer 45

short

Question 46

wavelengths of light emitted from cold object

Answer 46

long

Question 47

how does a fluorescent bulb work?

Answer 47

energy hits Hg-Ar mixture, invisible UV light is produced and absorbed by fluorescent coating, converted into visible light

Question 48

luminescence

Answer 48

the emission of light from a substance that has not been heated

Question 49

which colour has the shortest wavelength?

Answer 49

purple

Question 50

which colour has the longest wavelength?

Answer 50

red