waves and earthquakes

Question 1

what is light?

Answer 1

transverse wave
seen by eyes
travel through a vacuum
330 m/s

Question 2

when does refraction occur?

Answer 2

when the speed of a wave changes as it moves from one material to another

Question 3

what happens when light goes from more dense to less dense material?

Answer 3

bends away from the normal

Question 4

what happens when light goes from less dense to more dense material?

Answer 4

bends towards the normal

Question 5

what are the conditions for total internal reflection?

Answer 5

angle of incidence bigger than the critical angle

light passing from more dense to less dense material

Question 6

what are optical fibres used for?

Answer 6

telecommunications (transmission of information over long distances)

Question 7

how do optical fibres compare to copper wires?

Answer 7

better -
more secure 
higher capacity so more info 
higher quality so less interference 
less signal loss so less boosters needed

Question 8

how do optical fibres compare to satellites?

Answer 8

fibre optics carry more information, less time delay, cheaper and easier to repair, production costs are low

satellites are suitable for rough terraine, takes 3 or 4 to cover the world and are used with mobile devices

Question 9

what are the uses of TIR?

Answer 9

endoscopes and CT scans

Question 10

what is an earthquake?

Answer 10

vibration of the earth produced by tectonic activity

Question 11

what is an epicenter?

Answer 11

point on ground surface above the focus

Question 12

what is a focus?

Answer 12

where the rock breaks producing an earthquake

Question 13

what are p-waves?

Answer 13

longitudinal waves
fastest seismic wave
travel through solid and liquid

Question 14

what are surface waves?

Answer 14

travel across solid surface of earth
slowest waves
transverse and longitudinal
large amplitude and long wavelength

Question 15

what are s-waves?

Answer 15

transverse
slowest of body waves
travel only through solids

Question 16

where are p and s waves refracted?

Answer 16

in the mantle and outer core

Question 17

why do p and s waves refract in the mantle?

Answer 17

significant change in density, stiffness and then speed

Question 18

what is trilaturation?

Answer 18

distance of earthquake from 3 seismic stations

Question 19

how do you work out where an earthquake occurred?

Answer 19

s = d
—
t

Question 20

what speed do p and s waves travel at?

Answer 20

p - 8 km/s

s - 5 km/s

Question 21

how do you calculate lag time?

Answer 21

calculate distance travelled by each wave
d=s x t
t =(t+_)
expand and calculate