Question

1 D is equivalent to:

Options

• \[1\,m^{-1}\]

• \[1\,cm^{-1}\]

• \[1\,m^{1}\]

• \[1\,m\]

Answer 1

Since power is the reciprocal of the focal length measured in metres, its unit is the inverse metre. Hence \[1D = 1m^{-1}\].