Assume that the sun rotates about an axis through its centre and perpendicular to the plane of rotatin of the earth about the sun. The appearange of the sun, from any one pont on the earth, is shown. Light belonging to a particular spectral line, as received from the points `A, B, C` and `D` on the edge of the sun, are analyzed

Options

A. Light from all four points have the same wavelength
B. Light from C has greater wavelength than the light from D
C. Light from D has greater wavelength than the light from C
D. Light from A has the same wavelength as the light from B

Answer

C, D

Explanation

As point D is moving a wave from earth the light from this point will have a greater wave length and point C is moving toward earth, light from this point will have a short wavelength, point A and B are at rest in the observer's frame so lightfrom bothofthesepointswillhavesamewavelength.