Question

In the space charge limited region for vacuum tube diode for plate voltage 400 and 200 volts. The plate current and $ {{I}_{{{P}_{1}}}} $ and $ {{I}_{{{P}_{2}}}} $ have ratio:

• A. $ 1:2 $
• B. $ 2:1 $
• C. $ 1:2\sqrt{2} $
• D. $ 2\sqrt{2}:1 $

Answer 1

Answer: (D)

Thermionic current $ {{I}_{P}}\propto {{V}_{P}}^{3/2} $ $ \frac{{{I}_{{{P}_{1}}}}}{{{I}_{{{P}_{2}}}}}={{\left( \frac{400}{200} \right)}^{1/2}}=\frac{{{2}^{3/2}}}{1}=\frac{2\sqrt{2}}{1}=2\sqrt{2}:1 $