Question

a 12. Focal length of a double convex lens is 10 cm. By using this lens, Meena wants to get a real and enlarged image. At what distance will she place an object in front of the lens? a. More than the distance of 20cm b. Distance equal to 20cm c. Distance between 10cm and 20cm d. Less than the distance of 10cm​

Answer 1

Answer:

Explanation:

f=20cm

m=−2(red)

v=2u

Sign convention

u=−ve

v=+ve

f=+ve

Using lens formula,

v1​−u1​=f1​

⇒−2u1​−u1​=f1​

→u=−23f​=−23×10​=−15cm

Object should be placed at 15cm in front of the lens.