You can assume a bandwidth of $1MHz$ and a temperature of $25C.$

The photomultiplier has $10$ dynodes and an electron gain of $4$ for each dynode. Calculate the number of electrons emitted at the cathode during the measurement time. The measurement time, $t,$ is given by:

$t=\frac{1}{2f},$ where $f$ is the measurement bandwidth

Hint: Trace the electrical path from the measurement $($voltage out$)$ back to the PMT cathode and pay attention to units.