waves (reflection, refraction, lenses) COPY

Question 1

what is the relationship between the angle of incidence and the angle of reflection when waves are reflected

Answer 1

when waves are reflected the angle of incidence is equal to the angle of reflection

Question 2

what is the normal

Answer 2

the normal is a construction line perpendicular to the reflecting surface at the point of incidence

Question 3

describe the image in the plane mirror

Answer 3

-virtual (it cannot be touched or projected onto a screen) -upright (if you stand in front of a mirror, you look the right way up) -laterally inverted (if you stand in front of a mirror, your left side seems to be on the right in the reflection)

Question 4

Refraction

Answer 4

The change of direction of light waves when they pass from one medium to another at an interface

Question 5

which way does light refract when it enters a more dense medium

Answer 5

it refracts towards the normal

Question 6

which way does light refract when it enters a less dense medium

Answer 6

it refracts away from the normal

Question 7

what happens when waves travel along the normal

Answer 7

they are not refracted

Question 8

why are waves refracted

Answer 8

due to change of speed

Question 9

what can refraction by a prism lead to

Answer 9

dispersion (the separation of visible light into its different colours)

Question 10

what is the refractive index of a medium defined as

Answer 10

speed of light in vacuum (air) —————————————– speed of light in the medium

Question 11

what us the relationship between refractive index, angle of incidence and angle of refraction

Answer 11

sin (angle of incidence) refractive index = ———————————- sin (angle of refraction) sin i n = ——– sin r

Question 12

What is the relationship between refractive index and critical angle

Answer 12

1 refractive index = ———————– sin (critical angle) 1 n = ——— sin c

Question 13

what is the critical angle

Answer 13

the critical angle, c, is the angle of incidence at which maximum refraction occurs (when the angle of refraction = 90°)

Question 14

what is total internal reflection

Answer 14

total internal reflection is a special case of refraction, which occurs if the angle of incidence within the more dense medium is greater than the critical angle

Question 15

how can visible light go through optical fibres

Answer 15

visible light can be transmitted through optical fibres by total internal reflection

Question 16

what is an example use of light being transmitted through optical fibres by total internal reflection

Answer 16

the endoscope for internal imaging

Question 17

how does a lens form an image

Answer 17

a lens forms an image by refracting light. each section of a lens acts like a tiny prism, each section refracting light as it goes in and again as it comes out

Question 18

what happens with a convex lens

Answer 18

in a convex lens, parallel rays of light are refracted so that they come together (brought to a focus) at the principal focus (F)

Question 19

what is another name for a convex lens

Answer 19

a converging lens

Question 20

what can a converging lens be used as

Answer 20

a magnifying glass

Question 21

what is the nature of images produced by converging lens

Answer 21

converging lenses focus the rays of light to form a real image

Question 22

what is a real image

Answer 22

A real image is the image formed where the light rays are focussed.

Question 23

what is a virtual image

Answer 23

A virtual image is one from which the light rays appear to come but don’t actually come from that image like in a mirror.

Question 24

what is the focal length

Answer 24

the distance from the lens to the principal focus

Question 25

what is the focal length of a lens determined by

Answer 25

-the refractive index of the material from which the lens is made -the curvature of the two surfaces of the lens

Question 26

For a given focal length, the greater the refractive index, the …….. the lens

Answer 26

for a given focal length, the greater the refractive index, the flatter the lens. this means that lens can be manufactured thinner

Question 27

what happens in a concave lens

Answer 27

in a concave lens, parallel ray of light diverge as if coming from the principal focus

Question 28

what is another name for a concave lens

Answer 28

a diverging lens

Question 29

what does a diverging lens do

Answer 29

diverging lenses refract the parallel rays of light so that they spread apart from one another. This means that they form a virtual image

Question 30

what is the nature of an object defined by

Answer 30

P -position O -orientation (upright or inverted - relative to the object) T -type (real or virtual) S -size (diminished or enlarged - relative to the object)

Question 31

equation for calculating the magnification produced by a lens

Answer 31

image height magnification = —————————- object height

Question 32

what is the relationship between the power of a lens and the focal length

Answer 32

1 Power = ————- focal length 1 P = —– f