The potential difference between the emitter
and collector plates is measured by a voltmeter (V)
whereas the resulting photo current flowing in the circuit
is measured by a microammeter (mA) The photoelectric
current can be increased or decreased by varying the
potential of collector plate A with respect to the emitter
plate C The intensity and frequency of the incident light
can be varied, as can the potential difference V between
the emitter C and the collector A We can use the experimental arrangement of Fig