Question

How far from the lens must the film in a camera be, if the lens has a 4.6 cm focal length and is being used to photograph a flower 65 cm away? Equation: 1) = 1 + 1

Answer 1

Given,

Focal length is  

Object distance is  

Therefore, by equation

$\\\frac{1}{f} = \frac{1}{d_0} + \frac{1}{d_i} \\\\\\\frac{1}{0.046} = \frac{1}{0.65} + \frac{1}{d_i} \\\\\\\frac{1}{d_i} = \frac{1}{0.046} - \frac{1}{0.65} \\\\\\\frac{1}{d_i} = \frac{0.65 - 0.046}{0.65 * 0.046} \\\\\\d_i = \frac{0.65 * 0.046}{0.65 - 0.046} \\\\\\d_i = 0.0495 \ m \\\\d_i = 4.95 \ cm$

Therefore, the distance of the film from the lens is