Suppose the fractional efficiency of a metal surface with work function 1.40 ev is 1.0 × 10-18; that is, on average one electron is ejected for every 1018 photons that reach the surface. what would be the current of electrons ejected from such a surface if it were illuminated with 510 nm light from a 1.75 mw laser and all the ejected electrons took part in the charge flow?

The answer would be a

W= fd
where f is an applied force and d is the distance over which it is applied. when a parachuting skydiver is at constant velocity, he is experiencing "terminal velocity", the point at which his acceleration down is canceled out by air resistance. that means that the resisting force of the air is equal to his weight, but in the opposite direction. with this, we can solve for the work done by the force.
w = fd
w = (92.0)(9.81 m/s^2) (325)
w= 2.93 x 10^5 j
the value for work in this case is positive because it is pushing up on the skydiver, who has a downward force of gravity.
therefore the answer is 2.93 x 10^5 j