Unit 1.2 - Further Waves Flashcards
What is a critical angle of glass
42°
What is the critical angle of water
49°
What does TIR stand for
Total internal reflection
Refraction equation
Incident angle < Critical angle
Critical case equation
Incident angle = critical angle
Total internal reflection equation
Incident angle > critical angle
In the critical case, the wave passes ____________
Along the boundary
Two conditions for TIR
The light must be travelling from a more dense medium into a less dense medium
The angle of incidence must be greater than the critical angle
How to ensure T I are in optical fibre
Coat the fiber in cladding aids of a lower density
Collision point also known as
Focus
Epi - Latin
Surface
What is the inner core made of
Solid
What is the outer core made of
Liquid
Focus definition
Point from which the shockwaves emanate from, i.e. were tectonic plates collide
Epicentre definition
Point directly above the focus on the Earth’s surface
Where do you seismic waves start
At the focus
Type of primary wave
Longitudinal
Type of secondary wave
Transverse
Properties of primary wave
Travels at 7 km/s
Can travel through liquids and solids
Properties of secondary waves
Travels at 4 km/s
Can travel through solids only
The secondary wave shadow zone begins at
103°
Why is the secondary wave shadow zone occurred
Missed due to secondary waves not being able to go through liquid
In between what two angles is the primary wave shadow zone
103°-140°
Why is the primary wave shadow zone occurred
Missed due to refraction
Primary waves have ____Damage because…
Less
They are longitudinal
Secondary waves have ______ damage because …
More
They are transverse
What happens to secondary waves when outer core reached
Waves slow down to a stop
What happens to primary waves when inner core reached
Wave Velocity stays the same
What happens to primary waves when outer core reached
Slows down almost to a stop paragraph yet carries on
What happens to the speed of primary and secondary waves as the depth increases
Increases
What happens to the speed when waves cross boundaries
Changes rapidly
How to calculate time-lag
Start of secondary wave - Start of primary wave
How to calculate distance from epicentre
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How many stations needed to find epicentre
Three
