Optics

Question 1

what is white light?

Answer 1

a mixture of all colours of the rainbow

Question 2

how does light travel?

Answer 2

in waves

Question 3

how do rays travel?

Answer 3

in straight lines

Question 4

why is the sky blue?

Answer 4

blue light is scattered more than red light when it bends in a prism; when sunlight hits molecules, light bends a lot making the sky blue

Question 5

shadow

Answer 5

formed when a material blocks light

Question 6

transparent

Answer 6

material that transmits light easily; things can be seen through clearly

Question 7

transluscent

Answer 7

material that transmits some light; light is scattered , objects can still be seen but not distinctly

Question 8

material that blocks light; no light can penetrate through objects

Answer 8

opaque

Question 9

bioluminescence

Answer 9

luminescent; light emitted by living organisms i.e fireflies, jellyfish

Question 10

incandescence

Answer 10

incandescent; light is so hot that it glows, any object that emits visible light because it is heated to a high temperature

Question 11

chemiluminescense

Answer 11

luminescent; energy released in chemical reactions i.e glow stick

Question 12

flourescence

Answer 12

luminescent; phosphor absorbs uv radiation making it glow (fluorescent light tube)

Question 13

phosphorescence

Answer 13

luminescent; absorbs uv radiation or visible light, able to emit light after light source (which it is absorbing energy from) is removed

glow in the dark

Question 14

Light Emitting Diodes (LED)

Answer 14

luminescent; type of diode that provides light when electricity passes through it

diodes- semiconductors used to control direction of energy flow

p-n junction- formed by p-type semicon and n-type semicon; when current goes from p to n, light is emitted

Question 15

what are waves?

Answer 15

transfer of ENERGY (not matter) from one place to another

Question 16

medium

Answer 16

the matter that waves MOVE THROUGH

Question 17

vibration

Answer 17

when waves move THROUGH matter

Question 18

transverse waves

Answer 18

move up and down; in 1 direction - energy moves forward

Question 19

longitudinal waves

Answer 19

moves back and forth , series of compressions and rarefactions; energy moves in same direction as waves

Question 20

particles are squeezed

Answer 20

compression (crest)

Question 21

particles are stretched

Answer 21

rarefaction (trough)

Question 22

how big a wave is; how much energy is carried by wave

Answer 22

amplitude

Question 23

distance from crest to another crest or trough to another trough measured in hertz

Answer 23

wavelength

Question 24

wave speed formula

Answer 24

frequency x wavelength

WAVE FREQUENCY IS NOT WAVE SPEED

Question 25

human ear can hear _______ to ________ hertz

Answer 25

20 to 20 000

Question 26

spectrum

Answer 26

range of colours of visible light

Question 27

white light is composed of _______

Answer 27

all colours

Question 28

what determines the colour of an opaque object?

Answer 28

determined by the light (the colour) that is reflected to our eyes

Question 29

three additive primary colours

Answer 29

red blue green

Question 30

subtractive primary colours

Answer 30

yellow cyan magenta

Question 31

red and green make

Answer 31

yellow

Question 32

cyan is made by mixing

Answer 32

green and blue light

Question 33

red and blue

Answer 33

magenta

Question 34

what is colour blindness?

Answer 34

ability to only see shades of grey; defected cones lead to colour blindness

Question 35

complimentary colours for yellow

Answer 35

red and green

Question 36

complimentary colours of cyan

Answer 36

blue and green

Question 37

complimentary colour of magenta

Answer 37

blue and red

Question 38

rod and cone cells are located in _________

Answer 38

retina of the eye

Question 39

cone cells

Answer 39

detect colour

Question 40

rod cells

Answer 40

detect shapes, movement and shades of grey

Question 41

what happens when all three of additive primary colours are combined?

Answer 41

white light is produced