Angles of Nodal Lines (Two point light source)

[ND3G]

A two-point source operates at a frequency of 1.0Hz to produce an interference pattern in a ripple tank. The sources are 2.5cm apart and the wavelength of the waves is 1.2 cm.

Calculate the angles at which the nodal lines in the pattern are located far from the sources. (assume the angles are measured from the central line of the pattern.

Given:
f = 1.0Hz
d = 2.5cm
wavelength = 1.2cm

Analysis:
sin = ((n - 0.5)*wavelength)/d

Solution:
sin1 = ((1 - 0.5)1.2cm)/2.5 = 14 degrees
sin2 = ((2 - 0.5)1.2cm)/2.5 = 46 degrees
sin3 = ((3 - 0.5)1.2cm)/2.5 = undefined

Paraphrase:
Therefore, far from the sources the nodal lines are located at angles of 14 and 46 degrees to the central line of the pattern.

I really wasn't sure what this question was looking for so I just did what seemed most likely. Can someone let me know if I am on the right track here or missing the point? Thanks

 

[daniel_i_l]

That looks good to me.