CHAPTER 14

Question 1

what is important to remember about the angle of incidence when a light wave reflects

Answer 1

it will equal the angle of reflection

Question 2

why do the reflected and incident waves have the same wavelength

Answer 2

they have the same frequency and travel at the same speed

Question 3

what do light rays show

Answer 3

the direction the light waves are moving in

Question 4

what is the normal

Answer 4

a line that is perpendicular to the mirror

Question 5

what is the angle of incidence

Answer 5

the angle between the incident ray and the normal

Question 6

what is the angle of reflection

Answer 6

the angle between the reflected ray and the normal

Question 7

what three things is an image that is formed by a plane mirror

Answer 7

virtual, upright and laterally inverted -back to front

Question 8

what is a virtual image

Answer 8

one that is formed at the place where light rays appear to come from after they have been reflected

Question 9

why can you see a clear image when you look in a mirror

Answer 9

it has a smooth surface for specular reflection

Question 10

what is specular reflection

Answer 10

reflection from a smooth surface where parallel light rays are reflected In one direction

Question 11

what is diffuse reflection

Answer 11

reflection from a rough surface results in light rays being spread in different directions

Question 12

what happens when each point on the incident wavefront reaches a barrier

Answer 12

it creates a wavelet

Question 13

what do wavelets do

Answer 13

line up with other reflected wavefronts to create the reflected ray

Question 14

what happens to the direction of a light ray when it travels into a material that is denser

Answer 14

it moves towards the normal the angle of refraction is smaller than the one of incidence

Question 15

what happens to the direction of a light ray when it travels into a material that is less dense

Answer 15

moves away from normal angle of refraction

is greater than the one of incidence

Question 16

what is refraction

Answer 16

when a wave crosses a boundary between materials and is refracted

Question 17

why does refraction occur

Answer 17

waves travel at different speeds in different densities

Question 18

what is partial reflection

Answer 18

when some waves cross are reflected at a boundary and others lose energy so are refracted

Question 19

what is different about each colour

Answer 19

different frequency and wavelength

Question 20

what is a transparent object

Answer 20

something that transmits all light entering the object

Question 21

what is a translucent object

Answer 21

something that lets light pass through it but the light is scattered or refracted

Question 22

why are objects translucent

Answer 22

they have lots of internal boundaries so the direction pf light changes repeatedly

Question 23

what is an opaque object

Answer 23

something that absorbs all light that hits it

Question 24

how do appliances emit different coloured lights

Answer 24

they emit different wavelengths of light

Question 25

how do colour filters work

Answer 25

they absorb and transmit certain wavelengths

Question 26

what are the three primary light colours

Answer 26

red green blue

Question 27

why are red green and blue the three primary colours

Answer 27

they can be mixed to produce any other colour of light

Question 28

what do pigments do

Answer 28

absorb light of specific wavelengths and strongly reflect the rest

Question 29

why is a white surface white

Answer 29

it has no pigments it reflected all light that hits it

Question 30

why is a red book red

Answer 30

it has pigments that absorb all of the colours apart from red which it reflects

Question 31

what is produced when all of the primary colours are combined

Answer 31

white light

Question 32

what happens when light hits a black object

Answer 32

all light is absorbed

Question 33

what do colour filters do

Answer 33

filters wavelengths so only certain ones are absorbed or transmitted

Question 34

what would a blue filter do

Answer 34

absorb all the colours apart from blue which it reflected and transmits

Question 35

how does a lens work

Answer 35

it changes the direction of the light passing through it

Question 36

what does a convex lens do

Answer 36

it makes parallel light rays converge to a focus

Question 37

what is the principal focus/focal point of a lens

Answer 37

where the parallel rays are focused to

Question 38

uses of convex lens 3

Answer 38

magnifying glass camera correct long sightedness

Question 39

what does a concave lens do

Answer 39

makes parallel light rays spread out diverge

Question 40

what is the principal focus of a concave lens

Answer 40

where the rays appear to have come from

Question 41

use of concave lens

Answer 41

correct short sightedness

Question 42

what is the focal length of a lens

Answer 42

the distance from the lens to the principal focus

Question 43

equation for magnification from a lens

Answer 43

image height / object height

Question 44

if the magnification of an object is greater than 1 what does it tell you

Answer 44

the image is bigger than the object

Question 45

if the magnification of an object is less than 1 what does it tell you

Answer 45

the image is smaller than the object

Question 46

what is a real image

Answer 46

something that can be formed on a screen

Question 47

what does a convex lens do

Answer 47

it bulges outwards and causes light rays to converge at the principal focus

Question 48

what does a concave lens do

Answer 48

bulges inwards and causes light rays to diverge ash principal focus

Question 49

what is an axis

Answer 49

a line passing through the centre of the lens

Question 50

what is the principal focus of a convex lens

Answer 50

where the rays meet q

Question 51

what is the principal focus of a concave lens

Answer 51

where the rays appear to come from

Question 52

what is the focal length

Answer 52

the distance from the centre of the lens to the principal focus

Question 53

what are the three rules for refraction in a convex lens

Answer 53

a ray parallel to the axis refracts through the lens and passes through a principal focus a ray passing through the principal focus will refract through the lens and travel parallel to the axis a ray passing through the centre of the lens carries on in the same direction

Question 54

what are the three rules for refraction in a concave lenss

Answer 54

a ray parallel to the axis refracts through the lens and appears to have come from the principal focus a ray passing through the lens towards the principal focus will refract and travel parallel to the axis a ray passing through the centre of the lens carries on in the same direction

Question 55

what is a virtual image

Answer 55

when rays diverge so light from an object appears to be coming form a different place

Question 56

what three things do you need to say about an image to describe it

Answer 56

upright/inverted real/virtual magnified/diminshed

Question 57

what does the image created by a lens depend on 2

Answer 57

the focal length of the lens | the distance between the object and the lens

Question 58

what will an image formed by a concave lens always be

Answer 58

virtual and diminished

Question 59

what type of lens is used in a camera

Answer 59

convex

Question 60

when is a real image formed by a convex lens

Answer 60

when the object is further away from the principal focus