Question

A silicon diode has a forward voltage drop of \(0.7\ \mathrm{V}\). If it is connected in series with a \(1\,\mathrm{k}\Omega\) resistor to a \(5\ \mathrm{V}\) supply, then the forward current is

• A. \(3.3\ \mathrm{mA}\)
• B. \(5.7\ \mathrm{mA}\)
• C. \(5.0\ \mathrm{mA}\)
• D. \(4.3\ \mathrm{mA}\)

Hint:

For a silicon diode, \[ \boxed{ V_D\approx0.7\ \mathrm{V} } \] and \[ \boxed{ I=\frac{V_{\text{supply}}-V_D}{R}. } \]

Answer 1

The Correct Option is D

Step 1: Find the voltage across the resistor. The resistor voltage is \[ V_R = 5-0.7 = 4.3\ \mathrm{V}. \]

Step 2: Apply Ohm's law. \[ I = \frac{V_R}{R} = \frac{4.3}{1000} = 4.3\times10^{-3}\ \mathrm{A} = 4.3\ \mathrm{mA}. \] Hence, \[ \boxed{4.3\ \mathrm{mA}} \] Therefore, \[ \boxed{(D)} \] is the correct answer.