Question

Your camera's zoom lens has an adjustable focal length ranging from 77 to 224 mm. What is its range of powers

Answer 1

Answer: $0.446\ D\ \text{to}\ 1.298\ D$

Explanation:

Given

Camera has an adjustable focal length ranging from $77$ to $224$ mm

Power is given by Reciprocal of focal length in meter

Power corresponding to 77 cm

$\Rightarrow P=\dfrac{1}{0.77}\\\\\Rightarrow P=1.298\ D$

Power corresponding to 224 cm

$\Rightarrow P=\dfrac{1}{2.24}\\\\\Rightarrow P=0.446\ D$

Therefore, the range of the power is $0.446\ D\ \text{to}\ 1.298\ D$