The human eye can barely detect a star whose intensity at the earth's surface is $1\mathrm{.}61011$W$/$m$21\mathrm{.}61011$W$/$m$2.$

Part A

If the dark adapted eye has a pupil diameter of $7\mathrm{.}0$ mmmm $,$ how many photons per second enter the eye from the star? Assume the starlight has a wavelength of $550$ nmnm $.$

Activate to select the appropriates template from the following choices. Operate up and down arrow for selection and press enter to choose the input value typeActivate to select the appropriates symbol from the following choices. Operate up and down arrow for selection and press enter to choose the input value type

NN $=$

nothing