2) Power of the lens is -40, its focal length is
b) -40m c)-0.25m
a) 4m
d) -25m

Power of length is said to be reciprocal of focal length.

P=1/f

Explanation:

P= -40(negative sign shows it's concave lens)

f=?

P=1/f then,

f=1/P

f=1/(-40)

f= -0.025cm

-0.025*100(to convert it into meter)

f= -2.5 m

energy can be converted from one form to another, but it cannot be created or destroyed in ordinary chemical or physical means. do not understand what you are asking but hope this

i think the answer is a, hope this : )