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In a circuit with a forward-biased diode having a voltage drop of 0.5 \mathrm{~V} and a safe current limit of 10 \mathrm{~mA}, a battery with an EMF of 2.5 \mathrm{~V} is used. What is the minimum resistance value required to be connected in series with the diode to ensure that the current does not exceed the safe limit?

Option: 1

100 \, \Omega


Option: 2

150\, \Omega


Option: 3

200 \, \Omega


Option: 4

500 \, \Omega


Answers (1)

best_answer

Given:

Diode forward voltage drop, V_{\text {diode }}=0.5 \mathrm{~V}

Safe current limit, I_{\text {limit }}=10 \mathrm{~mA}=0.01 \mathrm{~A}

Battery EMF, E=2.5 \mathrm{~V}

To calculate the minimum resistance ( \left.R_{\min }\right) , we can use the formula: 

\begin{aligned} & V_R=E-V_{\text {diode }} \\ & R_{\text {min }}=\frac{V_R}{I_{\text {limit }}} \end{aligned}

Substituting the given values:

\begin{aligned} & V_R=2.5 \mathrm{~V}-0.5 \mathrm{~V}=2 \mathrm{~V} \\ & R_{\min }=\frac{2 \mathrm{~V}}{0.01 \mathrm{~A}}=200 \Omega \end{aligned}
Therefore, the correct option is (C) 200 \Omega \text {. }

Posted by

SANGALDEEP SINGH

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