Question #0f123

1 Answer
Feb 21, 2017

Phase angle of the light radiation.


“k” is often used for a particular constant, usually with a clarifying subscript. In this case we can use dimensional analysis to at least see what form it takes. Lambda “λ” is usually wavelength in this context, and ‘r’ would be a radius to define an circumference (2πr).

So if we use SI units with meters for length, we have a circumference divided by a wavelength will equal our ‘k’.
#k = (2*pi*r)/lambda#.
This is a dimensionless number that is the “phase angle” of the light. (Seeλ )

(distance from start)/wavelength = phase angle/#(2*pi)#
#x/lambda = phi/2*pi#
rearranged to #lambda = (2*pi*r)/k#. Where I have substituted ‘k’ for the ‘phi’ and ‘r’ for the ‘x’.

#k = (2*pi*r)/lambda#.