em waves types

Question 1

What are all em waves

Answer 1

Transverse

Question 2

where do all em waves travel the same speed in

Answer 2

a vacuum

Question 3

what speed do they travel in it

Answer 3

3x10 to the power of 8

Question 4

how do they transfer energy

Answer 4

from a source to an absorber

Question 5

give an example

Answer 5

ir radiation emitted from hot object absorbed by surrounding air

Question 6

what is the em wave spectrum ordered in

Answer 6

the increasing frequency and decreasing wavelength or increasing wavelength and decreasing frequency

Question 7

what is the part of the spectrum humans can see

Answer 7

visible light

Question 8

what is an alternating current made of

Answer 8

oscillating charges

Question 9

what does the frequency of the ac current determine

Answer 9

the frequency of wave we produce

Question 10

what device transmits and recieves the ac

Answer 10

transmitter and reciever

Question 11

what can we transfer using radio waves

Answer 11

nearly all types of information

Question 12

what are very short radio waves used for

Answer 12

fm radio or tv

Question 13

why do you get faulty radio signal when in the car

Answer 13

hills and surrounding other objects interfere with the direct
transmission path of the wave

Question 14

what uses medium radio waves used to send data

Answer 14

bluetooth

Question 15

what do oscilloscopes display

Answer 15

wave frequency of an alternating current

Question 16

what are 2 types of microwaves

Answer 16

ones absorbed by water molecules and ones not absorbed by water molecules

Question 17

what and how are the non water microwaves used for

Answer 17

communication using satelites. they pass through atmosphere which has a lot of water

Question 18

how are they used

Answer 18

recieved by satelite and transmitted back down to earth detected by satelite dish to get satelite tv

Question 19

how are water microwaves spread through food

Answer 19

conduction and convection

Question 20

what is ir radiation used for

Answer 20

ir cameras /cooking in oven and grills without penetrating surface of food/electric heaters

Question 21

how are oven and grills using ir radiation

Answer 21

metal is heated with ir and emits ir radiation

Question 22

how are live organisms detected by ir cameras

Answer 22

they are hotter then surroundings so emit more ir radiation and appear brighter on ir camera

Question 23

what allows visible light to be used for communication

Answer 23

optical fibres that transmit data fast over long distances without absorbing and or scattering light(specular)

Question 24

why are optical fibres used over copper wires

Answer 24

they can transmit much more data and there is less chance for it to be distorted in transmission

Question 25

what uses uv light that is human generated

Answer 25

sun beds

Question 26

what are x rays used for

Answer 26

viewing internal structure of the body

Question 27

what do staff operating x rays wear

Answer 27

lead aprons

Question 28

why are gamma rays used

Answer 28

to sterilise medical equipment and food and in medical tracers

Question 29

why are they used over boiling water

Answer 29

as they kill microorganisms without melting equipment or altering food

Question 30

what is the trade off

Answer 30

they can diagnose and treat disease but also ionise cells

Question 31

what is convex

Answer 31

a lense that bulges ouwards

Question 32

What is the focal point/principal focus

Answer 32

The point that rays of light converge

Question 33

how does a lens form an image and how does it help us to see an image better

Answer 33

they help us to see an image as sharper or larger(magnifying glass/microscope) it forms an image by refracting light

Question 34

what are real images always

Answer 34

inverted

Question 35

virtual image are made from

Answer 35

2 imaginary lines

Question 36

what rays do concave lenses produce

Answer 36

virtual images

Question 37

what are virtual images

Answer 37

always upright

Question 38

concave lenses always produce

Answer 38

upright virtual images and the further they are from the lens the larger they are

Question 39

do virtual images form projections on screens

Answer 39

no

Question 40

what images can come from concave lenses vs convex lenses

Answer 40

concave - virtual convex-virtual and real

Question 41

roygbiv

Answer 41

red orange yellow green blue indigo violet

Question 42

what has longest wavelength and highest

Answer 42

red has longest and violet has the shortest so the highest freq/energy

Question 43

what is specular reflection

Answer 43

reflection from a smooth surface in a single direction(eg mirror

Question 44

what is diffuse reflection

Answer 44

reflection from a rough surface that causes scattering(eg matte/why reflection cant be seen off a table)

Question 45

what is white light

Answer 45

a mixture of all colours in the soectrum

Question 46

the more freq/energy the more

Answer 46

the light is refracted

Question 47

How do colour filters work

Answer 47

They absorb certain wavelengths(colours) and transmit others

Question 48

The colour transmitted is

Answer 48

The colour of the filter

Question 49

Colour of an opaque object depends on

Answer 49

The wavelengths of light that are reflected the strongest

Question 50

wavelengths that are not reflected

Answer 50

are absorbed

Question 51

white light on a green surface will have

Answer 51

green reflected into our eyes

Question 52

object appears white

Answer 52

when all wavelengths re absorbed equally

Question 53

appears transparent when all light is transmitted an only some is reflected or absorbed

Answer 53

all light is transmitted an only some is reflected or absorbed

Question 54

body is in equilibrium when

Answer 54

it absorbs radiation at the same rate it emits radiation

Question 55

object appears black when all wavelengths are absorbed

Answer 55

when all wavelengths are absorbed

Question 56

Temperature can be regulated by

Answer 56

controlling how much incoming radiation is absorbed or emitted

Question 57

rescue teams use light coloured shiny emergency blankets

Answer 57

as they emit less radiation than dark matt surfaces keeping patient warm as less ir is emitted