Edexcel P1B Earthquake waves and optical fibres

OPTICAL FIBRES & EARTHQUAKE
WAVES…read more

Light travels down an optical fibre by
TOTAL INTERNAL REFLECTION.
This is where light hits the inside of the
glass at an angle greater than the
CRITICLE ANGLE.…read more

The critical angle for glass is around 42°.
Total internal reflection is used in optical fibres to
transmit pulses of light.
They are used in telecommunications to transmit
telephone conversations and data - including this
web page to your computer!
Whilst traditional copper wires can be used (and
indeed are for the first 500 m or so from your
phone) they cannot carry as much information and
suffer from magnetic interference.…read more

Seismic waves
P waves- primary, get there first
Pushing and pulling waves-longitudinal
Travels through solids and liquids
S waves- secondary move more slowly
Sidewase and shakey waves-
transverse.
Travel through solids not liquids…read more

There are four kinds of waves produced
by an earthquake. Two move over the
surface, causing damage, and two pass
through the Earth itself - called body
waves.
By studying body waves, scientists
worked out what the Earth is like inside:…read more

Both S and P waves travel throughout
the body of the earth, and can be picked
up by seismometers - machines that
record earthquakes - anywhere in the
world.
However, it turns out that S waves
cannot travel through the core, and only
P waves are recorded in some places:…read more