Question

Part A How far from a 30.0 −mm -focal-length lens must an object be placed if its image is to be magnified 3.00 × and be real?

Part B What if the image is to be virtual and magnified 3.00×?

Answer 1

Part A Given, Magnification, m= 3.00 het object distance u= -x mm um= b 2 = 3 (where v=image distance) on, v=3x as, Produced image is real, so, u will be positive. and focal length, f= 20mm Now, we know to te- t on, fu- ta bo on, ſo or, a = 4x30 Ost, 1 = 40 So, in part A, an object must be placed at a distance 40mm from the lens. Part, B How, if image is virtual, then u and u both will be negetive. We have 4-t = the tanto or 3u - to or a=30x2 ar x=20 il, in part, B, an object must be placed at a distance 20mm from the lens.