An object is located in a fixed position in front of a screen. Sharp image is obtained on the screen for two positions of a thin lens separated by 10 cm. The size of the images in two situations are in the ratio 3: 2. What is the distance between the screen and the object ?

Question

An object is located in a fixed position in front of a screen. Sharp image is obtained on the screen for two positions of a thin lens separated by 10 cm. The size of the images in two situations are in the ratio 3: 2. What is the distance between the screen and the object ? (A) 124.5 cm (B) 144.5 cm (C) 65.0 cm (D) 99.0 cm

Tardigrade Admin · Accepted Answer

(m1/m2) = (3/2) = ((D+10/D-10))2 D = 99 cm

Q. An object is located in a fixed position in front of a screen. Sharp image is obtained on the screen for two positions of a thin lens separated by $10 c m$ . The size of the images in two situations are in the ratio 3 : 2. What is the distance between the screen and the object ?

$124.5 c m$

$144.5 c m$

$65.0 c m$

$99.0 c m$

$\frac{m _{1}}{m _{2}} = \frac{3}{2} = (\frac{D + 10}{D - 10})^{2}$
$D = 99 c m$

Q. An object is located in a fixed position in front of a screen. Sharp image is obtained on the screen for two positions of a thin lens separated by 10cm. The size of the images in two situations are in the ratio 3 : 2. What is the distance between the screen and the object ?

124.5cm

144.5cm

65.0cm

99.0cm