Question

Why reverse bias is measure in microampere but forward bias in milliampere?

Answer 1

In the case of reverse biased the diode allows very less current and that very less current is of the order of microampere and this less current cannot be detected by any normal ampere meter so we measure it in milliampere

In the case of forward biased diode it allows more current in comparison to the reverse biased diode, the current flowing through the forward biased current is in the order of milliampere and it cannot be measured by a normal amperemeter so  it is measured in milliampere