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Question: Answered & Verified by Expert
In space charge limited region, the plate current ina diode is $10 \mathrm{~mA}$ for plate voltage $150 \mathrm{~V}$. If the plate voltagte is increased to $600 \mathrm{~V}$, then the plate current will be
PhysicsWaves and SoundVITEEEVITEEE 2010
Options:
  • A $10 \mathrm{~mA}$
  • B $40 \mathrm{~mA}$
  • C $80 \mathrm{~mA}$
  • D $160 \mathrm{~mA}$
Solution:
2427 Upvotes Verified Answer
The correct answer is: $80 \mathrm{~mA}$
In space charge limited region, the plate current is given by Child's law $i_{p}=K V_{p}^{3 / 2}$ Thus,
$$
\frac{i_{p 2}}{i_{p 1}}=\left(\frac{V_{p 2}}{V_{p 1}}\right)^{3 / 2}=\left(\frac{600}{150}\right)^{3 / 2}=(4)^{3 / 2}=8
$$
or, $i_{p 2}=i_{p 1} \times 8=10 \times 8 \mathrm{~mA}=80 \mathrm{~mA}$...(i)

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