A student focussed the image of a candle flame on a white screen by placing the flame at various distances from a convex lens. He noted his observations as :

Which set of observations is incorrect?

Options

A. u = 60 cm, v = 20 cm
B. u = 15 cm, v = 70 cm
C. u = 30 cm, v= 30 cm
D. u = 24 cm, v = 40 cm

Answer

B

Explanation

For this observation u = 15 cm i.e., the object is at the focus and the image must be formed at infinity and not 70 cm.