Question

$28\times {10}^{15}$ electrons reach the anode of a vacuum tube per second. If the power consumed is $896milliwatts$. What is the anode voltage?

• A. 100 V
• B. 200 V
• C. 300 V
• D. 400 V

Answer 1

Answer: (B)

200 V

Given:-

Number of electrons per second =$28\times {10}^{15}$ Power=$P$=$896\times {10}^{-3}W$

Solution:-

$P=V\times i$

Where,

$P$=power

$V$=voltage

$i$=current

$\therefore V=\frac{896\times {10}^{-3}}{28\times {10}^{15}\times e}$ ,Where $e$ = charge on an electron

$V=\frac{896\times {10}^{-3}}{28\times {10}^{15}\times 1.6\times {10}^{-19}}$

$\Rightarrow V=200V$