1. the current is directly proportional to the light intensity
2. the current begins in less than 1 nanosecond
3. photoelectrons are emitted only if the light frequency f exceeds a threshold frequency f-initial.
4. the threshold frequency depends on the type of metal from which the cathode is made.
5. if the potential difference is positive, the current does not change as deltaV increases; if deltaV is negative then the current decreases until stopping potential is reached
6.the value of Vstop(stopping potential) is the same for both weak and intense light | 
