We shine a red laser on a metal surface. The energy of the photons is larger than the work function of the metal, so electrons are emitted. Let's say N electrons are emitted every second. If we now replace the red laser with a green laser of exactly the same intensity, how many electrons are emitted every second?

1. N
2. more than N
3. less than N
4. We don't even know if any electrons are emitted - that depends on whether the energy of the photons from the green laser exceeds the work function of the metal.