power 4dA convex lens of power + 6D is placed in contact with a concave lens of power – 4D. What is the nature and focal length of the combination. see full answer. Start JEE NEET FoundationBox4d services offer statistics on 4d and Toto results for Singapore and Malaysia prediction. 4D search,Toto search,4d analysis, winning solution. Box4d Results 4D results ... [