P5 - Waves I Flashcards
Name the 2 types of interference
Constructive and Destructive
What experiment did Thomas Young come up with?
The double-slit experiment
- showed how light can diffract
What type of waves are used to transmit different types of communication and why?
Electromagnetic waves (EM) with different frequencies transmit different types of communication because they behave differently in the atmosphere.
At what frequency do radio waves and microwaves pass through the atmosphere? Also what does this mean for transmissions?
Between 30MHz and 30GHz.
Transmissions need to be in the line of sight. This is because they can’t reflect off of the atmosphere.
Why do interference patterns occur?
waves of equal frequency or wavelength overlap
What wavelengths diffract?
Long wavelengths.
At what frequency do radio waves and microwaves pass through the atmosphere? Also what does this mean for transmissions?
Between 30MHz and 30GHz.
Transmissions need to be in the line of sight. This is because they can’t reflect off of the atmosphere.
How do you get constructive interference with 2 sounds that are exactly the same?
They meet after travelling the same distance or a path difference equal to a wavelength
How do you get destructive interference with 2 sounds that are exactly the same?
They meet after travelling a path difference equal to half, one and a half, 2 and a half, etc. wavelengths
Define path difference
The difference between the distance 2 waves have travelled
Define interference path
A pattern of constructive and destructive interference
How do you achieve stable interference?
By using coherent wave sources
How do you get coherent wave sources?
1) Same frequency
2) They’re in-phase
3) They have the same amplitude
When are waves in-phase?
When they’re troughs line-up and their crests line-up
Name an example of a coherent source of waves for light
monochromatic light
What absorbs scatter microwaves when they are above 30GHz? Also what does this do?
Rain and dust in the atmosphere.
It reduces the strength of the signal.
What do waves do as they go through a narrow gap?
They diffract.
Which wavelength diffracts the most?
Long wavelengths.
Finish the sentence on diffraction: The longer the wavelength…
the more it diffracts.
When do you get maximum diffraction?
When the size of the gap is the same length as the wavelength.
Finish the statements on diffraction: When the gap is smaller
When the gap is bigger
1) the wave diffracts more
2) the wave only diffracts at the edges.
