I have recently been reviewing the photoelectric effect in a circuit in which a metal target has a light directed onto it, and any resulting electrons flow through an empty space to a second target, completing the circuit to which a battery is also attached. I have, however, had a few conceptual questions regarding such a circuit. If the energy of the incident photons is less than the work function of the metal, could raising the battery voltage cause current to flow? (My initial guess is no because presumably no electrons would be emitted and therefore the flow of current will have been interrupted.) If the voltage is 0 but the photon energy is greater than the work function, would current be flowing in the circuit? Is the stopping voltage affected by the number of incident photons (assuming each incident photon of sufficient energy ejects one electron)?