From It=ne, the number of electrons emitted by cathode k per second is n=Ie.

Maximum initial kinetic energy ekm = h (cλ? cλ0)

According to the kinetic energy theorem, the maximum kinetic energy EkA=Ekm+eU=eU+h(cλ? cλ0)

So the answer is: ie; eU+h(cλ？ cλ0)。