the tale of photoelectron!
Three laser guns labelled as 1,2 and 3 have power 2 watt,3 watt and 5 watt (not necessary in the same order) are used to produce photocurrent from metal plate. number of photons emitted by laser guns are 410^18 , 510^18 and 910^18 per sec. metal plate have threshold energy 4.510^ -19 J. neither the power nor the number of photons emitted by a particular laser is known and it is known that all capable photons emit a photoelectron. now answer the following : minimum photocurrent that must be passed through the circuit is?