Waves and the EM Spectrum

Question 1

what are all electromagnetic waves?

Answer 1

transverse

Question 2

what did herschel do?

Answer 2

discovered infrared by using coloured filters to notice that his telescope heated up different amounts. then he used prism to break up the visible light and put thermometer on different colours. there was no visible at the end of the spectrum, and the temperature there was the hottest. he had discovered infrared

Question 3

what did Ritter do?

Answer 3

used silver chloride which turns black when exposed to light and it turned black after when there were no visable rays at the end of the spectrum
he had discovered ultraviolet

Question 4

what is the equation and unit of intensity

Answer 4

intensity = power / area

Question 5

equation for wave speeds

Answer 5

wavespeed = frequency x wave length

Question 6

the law of reflection

Answer 6

angle of incidence equals the angle of reflection

Question 7

what are concave mirrors used for?

Answer 7

to focus light as each day obeys the law of reflection

Question 8

what are convex mirrors used for?

Answer 8

to spread out light as each ray obeys the law of reflection

Question 9

how to calculate a refractive index

Answer 9

3x10(8) divided by the speed in material

Question 10

the higher the refractive index…

Answer 10

the slower the speed of light

Question 11

the order of the electromagnetic spectrum

Answer 11

radio
microwave
infrared
visible
ultraviolet 
x-Ray
gamma ray

Question 12

radio waves uses and risk

Answer 12

uses- radio transmitter
walkie-talkies
terrestrial television
MRI

risks- very low energy so no evidence it causes harm but it does cause heating

Question 13

microwaves uses and risks

Answer 13

uses- microwave ovens
mobile phones
GPS

risks- heating and damage
not ionising

Question 14

infrared waves risks and uses

Answer 14

uses
remote controls
grilling food
thermal imaging camera

risks
burns

Question 15

uses of visible light and risks

Answer 15

allows us to see
camera

can cause burns and eye damage

Question 16

uses and risks of ultraviolet

Answer 16

security marks
killing bacteria

burns and ionising cause cancer

Question 17

uses and risks of x-rays

Answer 17

x-ray images
cat scans

ionising which can lead to cell mutation

Question 18

uses and risks of gamma rays

Answer 18

sterilisation
treating cancer

can cause cancer

Question 19

what is total internal reflection

Answer 19

it occurs when a wave inside a material no longer passed through an internal surface and is reflected instead

Question 20

THE CRITICAL ANGLE

Answer 20

Total internal reflection can only occur is light is shone at or past a certain angle
less than angle of incidence will result in refraction
equal to critical angle means no light leaves the material
greater than angle results in reflection

Question 21

refractive index equation

Answer 21

refractive index = 1 / sin(critical angle)

Question 22

speed of light

Answer 22

3x10(8) m/s