power 4dhave found 30749 great 4d Desn Powerpoint templates for free. More animated ppt about 4d Desn free Download for commercial usable,Please visit . FollowTo find the focal length of the combination of two thin lenses in contact, we can follow these steps: Step 1: Identify the Powers of the Lenses We have two lenses: - Lens 1 has a power ( P1 = +4