Question

An object is height 6 cm is placed perpendicular to the principal axis of a concave lens of focal length 5 cm. Use lens formula to determine the position, size and nature of the image if the distance of the object from the lens is 10 cm.

Answer 1

h=6cm
f= -5cm
u= -10cm
=>1/v=1/u+1/f
=1/-10+1/-5cm
=-1-2/10cm
=-3/10cm
=>v =-10/3cm
=-3.33cm
Hence,the image will form at the same side of object,3.33cm away from the lens
Now,m=h'/h=v/u
=h'/6=(-10/3)/-10
=h'/6=1/3
=h'=2 Ans
Hence the size of image is 2cm
nature of image is real and inverted

Answer 2

Answer:

Explanation:

Given :-

h = 6 cm

f = - 5 cm

u = - 10 cm

v = ?

Solution :-

1/f = 1/v + 1/u

1/v = 1/f + 1/u

⇒ 1/v = 1/- 5 + 1/- 10

⇒ 1/v = 1/- 5 - 1/10

⇒ 1/v = - 1 - 2/10

⇒ 1/v = - 3/10

⇒ v = - 3.3 cm

h'/h = + v/u

⇒ h'/6 = - 3.3/- 10

⇒ h' = 6 × 3.3/10

⇒ h' = 19.8/10

⇒ h' = 1.98 cm.

Hence, the size of the image is 1.98 cm.