Optics Question 888

Question: The angle substanded by the first diffraction minimum for a point source viewed in the hydrogen line at 1420 MHz with a radio telescope having an aperture of 25 m is:

Options:

A) 0.8

B) 0.64

C) 1.2 

D) 2.2

Show Answer

Answer:

Correct Answer: C

Solution:

[c] λ=cf=3×1081420×106=0.214m

sinθ=1.22λd=1.22×0.21925=0.010 or θ=0.6o , and 2θ=1.2o



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