Waves Flashcards
What is frequency?
The number of complete waves passing a certain point each second.
What is meant by the term “period” in waves?
The amount of time it takes for a complete wave to pass a point.
What is amplitude?
The maximum displacement of a point on a wave from its rest position.
What is wavelength?
The length of a full cycle of a wave.
What are the three types of transverse waves?
> ripples in water.
electromagnetic waves.
↳ e.g. light.
waves on a string.
What are transverse waves?
Oscillations perpendicular (at 90°) to direction of energy transfer.
What are longitudinal waves?
Oscillations parallel to direction of energy transfer.
What is wave speed?
Speed at which a wave transfers energy or speed the wave moves at.
What is the formulae for wave speed?
wave speed = frequency x wavelength
v = f x ℷ
m/s Hz m
What is the process of measuring the speed of sound?
> speak attached to signal generator of specific frequency.
waves detected at each microphone shown as separate waves.
↳ move one microphone until waves line up.
↳ distance between microphones is now equal to one wavelength.
↳ use wave equation to find speed.
What is refraction?
When a wave changes direction as it crosses a boundary between two materials at an angle to the normal.
What happens when a wave refracts slows down?
The wavelength decreases and bends towards normal.
What happens when the wave refracts speeds up?
The wavelength increases and bends away from normal.
What is the electromagnetic (EM) spectrum?
radio waves ⟶ microwaves ⟶ infrared ⟶ visible light ⟶ ultraviolet ⟶ x-rays ⟶ gamma rays.
What happens to the frequency, wavelength and colour as you go down the electromagnetic (EM) spectrum?
The frequency increases, the wavelength decreases and the colour goes from red to violet.
What are some facts on EM waves?
> they are transverse.
transfer energy from source to absorber.
travel at same speed in air or vacuum.
How are radio waves produced?
> alternating current supplied which is shown on an oscilloscope.
↳ electrons oscillate producing radio waves in the transmitter.
↳ emitted radio waves transfer energy.
↳ radio waves absorbed causing electrons in receiver to oscillate
in the receiver.
↳ alternating current of same frequency as radio waves
induces in receiver.
What are the uses of radio waves?
> TV.
> radio.
What are the uses of microwaves?
> satellite communications.
> cooking.
What are the uses of infrared radiation?
> electric heaters.
cooking.
infrared cameras.
What are the uses of visible light?
Communications through optical fibres.
What are the uses of UV waves?
> energy efficient lights.
> sun tan beds.
What are the uses of x-rays and gamma rays?
> medial imaging.
> medical treatments.
What is a radiation dose?
The measure of the risk of harm to body tissues due to exposure to radiation.
[measured in sieverts]
