Question

A

How far from a 59.0-mm-focal-length lens must an object be placed if its image is to be magnified 2.50× and be real? Express your answer to three significant figures and include the appropriate units.

B

How far from a 59.0-mm-focal-length lens must an object be placed if its image is to be magnified 2.50× and be virtual? Express your answer to three significant figures and include the appropriate units.

Answer 1

A)

lens formula in cartesian system,

since magnification is real and it is 2.5x. let distance of object from lens is u. since object is in the left side of lens, so d_0=-u

u=82.6 mm

So, u=82.6 mm distance from the lens object should be placed.

part(B)

since magnification is virtual, magnification will be +2.5

since magnification is real and it is 2.5x. let distance of object from lens is u. since object is in the left side of lens, so d_0=-u

using lens formula,

u=35.4mm distance from lens object should be placed to get that magnification of 2.5x virtual