Question

The silicon diode shown in the figure is rated for a maximum current of $100mA$. Calculate the minimum value of the resistance of the resistor to avoid breakdown of diode $R$. Assume the forward voltage drop across the diode to be $0.7V.$

• A. $70\Omega$
• B. $16\Omega$
• C. $193\Omega$
• D. $39\Omega$

Answer 1

The correct option is C $193\Omega$

Using Formula V=IR

$R=\frac{V}{I}$

When current is maximum, then the resistance is minimum.

Given, $I=100mA=100\times {10}^{-3}A=0.1A$

The voltage across the circuit $=20V-0.7V=19.3V$

So; $R=\frac{V}{I}=\frac{19.3}{0.1}=193\Omega$