Question

you have two lenses of focal length + 20 cm and minus 20 CM write the nature of each lens which of the two lens can form a virtual and magnified image of an object placed 15 cm from the lens draw Ray diagrams​

Answer 1

The first lens with + 20 cm focal length is convex lens and it has converging nature

The second lens with -20 cm focal length is concave lens and it has diverging nature

since concave lens always produces diminished image, the lens mentioned in the question should be convex lens

u = -15 cm

f= 20cm

using mirror formula

1/f= 1/v- 1/u

1/v = 1/f+1/u

= 1/20-1/15

= -5/300

v = -60 cm

attachment above gives you the Ray diagram