Question

Graph of position of image vs position of a point object from a convex lens is shown in the figure. The focal length of the lens is –

• A. (0.50 ± 0.05) cm
• B. (5.00 ± 0.05) cm
• C. (0.50 ± 0.10) cm
• D. (5.00 ± 0.10) cm

Answer 1

Answer: (B)

(5.00 ± 0.05) cm

Answer 2

2f = 10

f = 5 cm

$\frac { 1 } { \mathrm { f } }$ = –

=

df = f²

u = 10, v = 10, du = $\frac { 1 } { 10 }$, dv = $\frac { 1 } { 10 }$

so df = 25$\left( \frac { 1 } { 10 ( 10 ) ^ { 2 } } + \frac { 1 } { 10 ( 10 ) ^ { 2 } } \right)$ = 25$\left[ \frac { 2 } { 10 \times 100 } \right]$

df = 0.05 so (5.00 ± 0.05) cm.