Power (P) of a lens is given by reciprocal of focal length (f) of

power 4dTranscript. Question 39 If the power of a lens is − 4.0 D, then it means that the lens is a (A) concave lens of focal length −50 m (B) convex lens of focal length +50 cmDemension : 23.5 x 17.5 x 5.2 cm. Output Power in 4 ohm : 1 x 1500 W. Output Power in 2 ohm : 1 x 3000 W. Output Power in 1 ohm : 1 x 4500 W.