question_answer

Explain with reason, how the resolving power of an astronomical telescope will change when (i) frequency of the incident light on the objective lens is increased, (ii) focal length of the objective lens is increased, and (Hi) aperture of the objective lens is halved.                             

Answer:

                R.P. of an astronomical telescope \[=\frac{D}{1.22\lambda }=\frac{Dv}{1.22c}\] (i) When frequency of the incident light is increased, the resolving power of the telescope increases. (ii) When the focal length of the objective lens is increased, the resolving power does not change. (iii) When aperture of the objective lens is halved, the resolving power of the telescope is also halved.