Question

focal lenght of concave lens of -0.5

Answer 1

A person cannot see objects beyond 2m

Answer 2

Is -0.5 the power of lens .

If it is then

Power = 1 / focal length ( in metre)

-0.5 = 1 / f

So, f = 1 / -0.5

f = -2 metre

Hope this will help you....