If a lens can converge the sun rays at a point 20 cm. away from its optical centre, the power of this lens is –
A. + 2D
B. – 2D
C. + 5D
D. – 5D
Answer:C
If a lens can converge the sun rays at a point 20 cm. away from its optical centre, the power of this lens is –
A. + 2D B. – 2D C. + 5D D. – 5D