Question

Graph of position of image versus position of point object from a convex lens is shown. Then, focal length of the lens is

• A. $0.50\pm 0.05cm$
• B. $0.50\pm 0.10cm$
• C. $5.00\pm 0.05cm$
• D. $5.00\pm 0.10cm$

Answer 1

Answer: (D)

$5.00\pm 0.10cm$

$\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\Rightarrow f=5cm$
$f=\frac{uv}{u+v}$
$\frac{\Delta f}{f}=\left|\frac{\Delta u}{u}\right|+\left|\frac{\Delta v}{u}\right|+\frac{\left|\Delta u\right|+\left|\Delta v\right|}{\left|u\right|+\left|v\right|}$
$\Delta f=0.15$
The most appropriate answer is (d) i,e,. 5.00 ± 0.10 cm