Wavefronts

Rays are parallel to a wavefront.

How is cylindrical wavefront formed?

Intensity of a point source is $0.2 \raisebox{1ex}{$w$}\!\left/ \!\raisebox{-1ex}{$m^2$}\right.$ at a place. If the distance of source and power are doubled the intensity at that place becomes to

Two waves having the intensities in the ratio $9:1$ produce interference. The ratio of maximum to minimum intensity is equal to

Cotyledons are also called-