Question

Choose which of following condition is not required for a waveguide to exist.

(a) The dimensions should be in accordance with desired frequency

(b) Cut-off frequency should be minimum 6GHz

(c) The shape should be spherical

(d) No specific condition is required for waveguide design

This question was addressed to me in an online interview.

This intriguing question originated from Spherical Coordinate System topic in portion Coordinate Systems and Transforms of Electromagnetic Theory

Answer 1

Right option is (c) The shape should be spherical

To explain: A waveguide need not be spherical, it has to be rectangular or circular, as it violates the propagation of the wave.