Consider the function f(x) = cos(b*sqrt of x), where b= 6.28 cm^-0.5.
a) Argue that this wave has crests at x=0.1 cm, 4cm, 9cm, and so on.
b) sketch a graph of this function , and argue that it looks like a wave whose wavelength is increasing as x increases .
c) estimate the local wavelength of this function at x=4.0cm by averaging the distance to adjacent crests on either side.
d) compute the local wavelength of this function at x=4.0cm and compare with your answer for part c .