Observe the water ripples in the video above ..uniform water patterns are formed by 2 sources of ripple. These sources are coherent to each other. What does it mean by coherent sources???
coherent = waves produced at same frequency, amplitude and in phase
This interference pattern can be illustrated in diagram below..
Ok now..its time to describe what can be seen in the diagram..
i. - points where the crest meet crest or trough meet trough is known as antinode.
line joining these points is known as antinode line
ii. - points where crest meet trough is known as node.
line joining these points is known as node line
From this interference phenomena we can also calculate the wavelength (λ). This is given by formula
λ = ax
D
a = distance between 2 coherent sources
x = distance between 2 consequtive node lines (or antinodal lines )
D = distance from coherent sources to the point of measurement of x
Ok..usually in SPM they will test you whether u know how to relate changes in a with respect to x & D.
Its about your maths skill..if u r gud in algebra..than it would be easy.
To let u understand this better, try this animation! (u need to have java applet installed)
2 comments:
last week our group held a similar discussion on this topic and you point out something we have not covered yet, appreciate that.
- Kris
nice post. thanks.
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