light and the electromagnetic spectrum

Question 1

what do all electromagnetic waves have in common?

Answer 1

• all are transverse waves
  -all travel at the same speed in a vacuum (3x10^8)
  -transfer energy from a source to an observer

Question 2

an example of a electromagnetic wave transferring energy from a source to an observer

Answer 2

all objects emitting infrared radiation, the more hotter the object the more radiation emitted

Question 3

what is the electromagnetic spectrum in order

Answer 3

gamma rays
x rays
ultra violet
visible light
infrared
microwaves
radio wave

Question 4

which ways does it increase in wavelength and frequency

Answer 4

gamma rays have the shortest wavelength and highest frequencies.
radio waves have the longest wave lengths and the shortest frequencies

Question 5

uses and properties of radio waves

Answer 5

• lowest frequency
• longest wavelength
• used to transmit radio broadcasting and tv programmes

Question 6

uses of micro waves

Answer 6

• used for communication and satellite transmissions and mobile phones
• to heat food in a microwave

Question 7

dangers of micro waves

Answer 7

• heats water in food, when digested can cause internal heating of body cells

Question 8

uses of infrared radiation

Answer 8

• can be used as communication at short distances
• security systems have sensors to detect infrared radiation which comes off of intruders

Question 9

danger of infra red radiation

Answer 9

can lead to skin burns if there is too much contact

Question 10

uses of visible light

Answer 10

• lightbulbs can made to emit visible light
• cameras made to detect visible light

Question 11

uses of ultra violet

Answer 11

• detecting forged bank notes
• disinfecting water by killing micro organisms
• fluorescent lamps

Question 12

the visible light spectrum

Answer 12

red ( closer to infrared/micro/radio)
orange
yellow
green
blue
indigo
violet ( closer to gamma)

Question 13

dangers of using ultra violet

Answer 13

damage to surface cells and eyes, can lead to skin cancer and eye condition

Question 14

uses of x - rays

Answer 14

• observing the insides of objects
• airport security scanners
• medical x -rays to see the conditions of the body

Question 15

uses of gamma rays

Answer 15

• sterilise food and medical equipment
• the detection of cancer and to treat cancer

Question 16

dangers of using x-rays and gamma rays

Answer 16

can cause mutations to cells and damage cells in the body

Question 17

how does the body stay a constant temp. in relation to radiation

Answer 17

the body must absorb and radiate the same average power for radiation for the temperature of the body to stay the same

Question 18

what happens if the body gives out more radiation and absorbs less radiation

Answer 18

• the body lets out more radiation
• so the temperature of the body will decrease

Question 19

what happens if more radiation absorbed increases and the less radiation is emitted

Answer 19

• more radiation kept in the body
• so the earth will heat up

Question 20

Explain the effects of differences in the velocities of electromagnetic waves in different substances

Answer 20

• Since the wave travels at different velocities in different substances
• this can lead to the wave changing direction

Question 21

the earth energy balance

Answer 21

for the earth to stay the same temperature
it must radiate the same amount of energy as being let out into the atmosphere

Question 22

explain the green house effect

Answer 22

-radiation from the sun reaches the earth surface
-some of the radiation is absorbed but most if reflected
- the some of the emitted radiation is absorbed by green house gases in the atmosphere
- this causes the earth to heat up

Question 23

what do all the colours together make up

Answer 23

white light

Question 24

what is specular reflection

Answer 24

where light is reflected evenly on very smooth surfaces.

Question 25

what is Diffuse reflection

Answer 25

reflected light is scattered due to having a rough surface so light goes in all directions

Question 26

how do we perceive light

Answer 26

When white light hits a coloured surface, some of the colours that make up the colour of the object is reflected and the colours that don’t make up the object is absorbed
For example - a red cube will absorb all the colours in white light but will reflect the colour red so a person will be able to the see the cube as red

Question 27

how do filters work

Answer 27

When white light goes through a blue filter, the filter will absorb all the other colours in the white light and will transmit ( allow through) blue light.