Vacuum diode is an electronic device that allows the electric current in  .(cathode to anode) and blocks the electric current in another direction (anode to cathode).

The space charge limited current in a diode is $2 \mathrm{mA}$ at $20 \mathrm{V}.$ At what voltage its value will be $16 \mathrm{mA}.$

Correct the following sentence:

The space charge limited current varies directly as the square root of plate current.

The space charge limited current in a diode is $16 \mathrm{mA}$ at $80 \mathrm{V}.$ At what voltage its value will be $128 \mathrm{mA}.$ (Write the numerical answer in terms of $\mathrm{V}$.)