Light and the EM Spectrum - topic 4

Question 1

what happens when a light ray hits the surface

Answer 1

it reflects off the surface

Question 2

what is the law of reflection

Answer 2

the angle of incidence = angle of reflection

Question 3

what is refraction

Answer 3

the change in direction of a wave passing from one medium to another is caused by its change in speed

Question 4

what happens if the light wave is going from a less dense medium to a more dense medium

Answer 4

propagation of light will slow down and will bend towards the normal

Question 5

what are the 2 types of reflection

Answer 5

specular reflection and diffuse reflection

diffuse diffusion

Question 6

what is specular reflection

Answer 6

when reflection is perfect due to reflection from the smooth surface

Question 7

what is diffuse reflection

Answer 7

reflection is imperfect due to a rough surface

Question 8

colours of visible light from longest to shortest

Answer 8

red
orange
yellow
green
blue
indigo
violet

Question 9

why are all colours revealed when white light passes through a prism

Answer 9

all colours individually have different wavelengths and travel at different speeds so are refracted by different amounts

Question 10

what happens when white light hits a coloured surface

Answer 10

white light is absorbed along with all of its colours aside from the colour of the object

Question 11

what are the two types of lenses

Answer 11

convex

concave

Question 12

what type of image does convex lens form

Answer 12

real image

Question 13

what type of image does concave lens form

Answer 13

virtual image

Question 14

what type of waves are EM waves

Answer 14

transverse waves

Question 15

order of EM waves from longest to shortest

Answer 15

radiowaves, microwaves, infrared, visible, ultraviolet, x-rays, gamma rays

Question 16

the higher in temp an object is……

Answer 16

the more infrared radiation it emits

Question 17

amount of energy the object absorbs must be……

Answer 17

the same as the amount of energy the object radiates

Question 18

what colour is the best emitter and absorber of infrared radiation

Answer 18

Matte Black

Question 19

what colour is the best reflector of infrared radiation

Answer 19

white

Question 20

harmful effects of microwaves

Answer 20

internal heating of body cells

Question 21

harmful effects of infrared

Answer 21

skin burns

Question 22

harmful effects of UV light

Answer 22

damage to skin cells and eyes, leading to skin cancer and eye conditions

Question 23

harmful effects of x-rays/ gamma rays

Answer 23

mutation/damage to cells in the body

Question 24

uses of radio waves

Answer 24

broadcasting, communications, satellite transmissions

Question 25

uses of microwaves

Answer 25

cooking, communication, satellite transmissions

Question 26

conditions for total internal refraction

Answer 26

light ray has to go from more to less dense medium | the angle of incidence has to be greater than the critical angle

Question 27

uses of infrared

Answer 27

cooking, thermal imaging, short-range communication, tv remote controls

Question 28

uses of visible light

Answer 28

vision, photography

Question 29

uses of UV

Answer 29

security markings, disinfecting water, detecting forged banknotes

Question 30

uses of x-rays

Answer 30

airport security scanners, medical x-rays

Question 31

uses of gamma rays

Answer 31

sterilising food and medical equipment and detecting cancer and its treatment

Question 32

what is total internal reflection

Answer 32

where the ray is reflected back into the first material instead of being transmitted into the new material

Question 33

what are the two types of lenses

Answer 33

converging and convex

Question 34

what is focal length

Answer 34

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

Question 35

what type of images do converging lens form

Answer 35

real images

Question 36

what type of images are formed by diverging lens

Answer 36

Upright, diminished and virtual images

Question 37

when is a real image formed

Answer 37

when the light rays from a point on an object come together to form an image

Question 38

when are virtual images formed

Answer 38

when light rays don't actually come together to form an image

Question 39

what do you need to say when describing an image

Answer 39

how big it is compared to the object whether it is upright or inverted whether it is real or virtual

Question 40

how does the focal length and shape of a lens affect its power

Answer 40

the shorter the focal length and the more curved the lens is, the more powerful the lens

Question 41

differences between converging and diverging lenses

Answer 41

converging lenses can produce real or virtual images and diverging can only produce virtual images converging lens converge light, diverging lens diverge lens

Question 42

what speed do EM waves travel at in a vacuum

Answer 42

at the same speed

Question 43

what happens if the average power emitted by an object is larger than the average power absorbed by the object

Answer 43

the object will cool down

Question 44

what happens if the average power emitted by an object is smaller than the average power absorbed by the object

Answer 44

the object heats up

Question 45

what colour is the best absorber and emitter of radiation

Answer 45

black

Question 46

what type of surface is the best absorber and emitter of radiation

Answer 46

matt

Question 47

when does total internal reflection occur

Answer 47

when a wave is travelling into a less dense material AND when the angle of incidence is larger than the critical angle

Question 48

what types of wave is a sound wave

Answer 48

longitudinal

Question 49

what type of wave is a light wave

Answer 49

transverse

Question 50

what speed do all EM waves travel at in a vacuum

Answer 50

3x10^8 m/s

Question 51

what happens if an atom absorbs energy

Answer 51

some of its electrons move to higher energy levels

Question 52

what happens when each electron falls back down to a lower level

Answer 52

an em wave is produced

Question 53

when are gamma rays produced

Answer 53

when there's a change in the nuclei of atoms

Question 54

when are gamma rays emitted

Answer 54

when the nucleus needs to get rid of extra energy

Question 55

how are radio waves produced

Answer 55

using an alternate current in an electrical circuit . As charges oscillate they produce oscillating electric and magnet fields.

Question 56

what does intensity and wavelength distribution depend on

Answer 56

their temperature