What is the position and nature of image formed by lens combination shown in figure? (f1, f2 are focal lengths)

Question

What is the position and nature of image formed by lens combination shown in figure? (f1, f2 are focal lengths) (A) 70 cm from point B at left; virtual (B) 40 cm from point B at right; real (C) 20/3 cm from point B at right , real (D) 70 cm from point B at right, real

Tardigrade Admin · Accepted Answer

For first lens (1/V) - (1/-20) = (1/5) V= (20/3) For second lens V= (20/3) - 2 = (14/3) (1/V) - (1/(14)3) = (1/-5) V = 70 cm

Q. What is the position and nature of image formed by lens combination shown in figure? $(f_{1}, f_{2}$ are focal lengths)

$70 c m$ from point $B$ at left; virtual

$40 c m$ from point $B$ at right; real

$20/3 c m$ from point $B$ at right , real

$70 c m$ from point $B$ at right, real

For first lens
$\frac{1}{V} - \frac{1}{- 20} = \frac{1}{5}$
$V = \frac{20}{3}$
For second lens
$V = \frac{20}{3} - 2 = \frac{14}{3}$
$\frac{1}{V} - \frac{1}{\frac{14}{3}} = \frac{1}{- 5}$
$V = 70 c m$

Q. What is the position and nature of image formed by lens combination shown in figure? (f1​,f2​ are focal lengths)

70cm from point B at left; virtual

40cm from point B at right; real

20/3cm from point B at right , real

70cm from point B at right, real