An astronomical telescope has an objective of diameter 20 cm with a focal length of 180 cm. the telescope is used with an eyepiece of focal length 30 mm. what is the angular magnification of this telescope?

By definition;
M = fo/fe

Where,
M = Angular magnification
fo = Focal length of objective lens
fe = Focal length of eyepiece lens

From the information given;
M = 180/30 = 6

Aform of energy that is reflected or emitted from objects in the form of electrical and magnetic waves that can travel through space. there are many forms of  electromagnetic  energy including gamma rays, x rays, ultraviolet radiation, visible light, infrared radiation, microwaves and radio waves.