P6 - Waves Flashcards
What is a transverse wave?
Vibrate perpendicular to direction of energy transfer
What is longitudinal wave
Vibrate parallel to direction of energy transfer
What direction do magnetic fields go?
North to south
Example of transverse wave
Light wave
Example of longitudinal wave
Sound
What is the stationary point of two oscillating waves called?
A node
Amplitude is distance from ___ to what
Crest/trough to line of equilibrium (NOT full height)
What is frequency
Number of waves passing a point each second
When lines a spread apart in a longitudinal wave what is this called?
Rarefaction
When waves are close together in a longitudinal wave what is this called?
Compression
Wavelength varies ____ and amplitude varies ___ (in terms of sound)
Pitch
Volume
What is the time period of a wave
Time taken for a complete oscillation
Give a an equation linking frequency and time period
f = 1/T (capital T)
We measure frequency in ___
Hz (Hertz)
Give an equation linking velocity of the wave, wavelength and time period
V = lambda / Time period
V = wavelength / time period
What is the wave equation?
V = f x lambda
How fast does light travel in a vacuum?
3 x 10 o the power 8 m/s
In what material does light move slowest
Diamond
Describe refraction
As light slows down and enters a denser material it bends towards the normal
(Sometimes describe the car?)
As light speeds up after leaving the material it bends away from the normal
Always draw:
Incident ray
Refracted ray
Normal
When drawing a diagram with an incident ray, refracted ray, and then one out the other side what happens?
The refracted ray is also now an incident ray for light going from the glass to the air
The ray coming out is hence refracted
What are EM waves?
Energy waves
Transverse can travel through a ___ but longitudinal can’t
Vacuum
Give a nemonic for the EM spectrum
Rude men in vans usually exit Greenwhich
Give the EM spectrum
Radio
Microwaves
Infrared
Visible
Ultraviolet
X rays
Gamma rays
Radio has high or low wavelength
High
Microwaves have a high/low wavelength
High
Microwaves can travel in ____ lines better than radio waves as they have higher ____
Straight
Energy
What type of radiation is infrared?
Heat
Infrared can be used for communication true or false
True
How is visible light produced?
Electrons fall from higher to lower energy states
Visible light is used in ___ ____ cables
Fibre optic
UV can be used for energy ___ lights
Efficient
(Fluorescence)
What is x ray used for
Detecting dense things
What is gamma radiation used for
Medicine
Nuclear bombs
Killing harmful bacteria, sterilising surgical equipment, killing cancer cells
UV light can be used to sterilise ___ and kill ____ and detect ___
Water
Bacteria
Forgery
Infrared radiation is for __- distance communication
Short
How can infrared radiation be used in medicine
Detect cancerous tumours which give off more heat than other parts of the body
Give 3 methods of energy transfer
Convection conduction and radiation
Infrared is emitted by ___ stuff and __ stuff
Hot and large
If an object is cooler than surroundings it ___ more IR radiation until it reaches same temperature
Absorbs
