HC Verma Chapter 45 Problem 7

Problem Statement

A p-n junction diode has saturation current 10 mA. Find current at forward bias 0.5 V at 300 K.

Key Concepts

Diode equation, forward bias

Relevant Formulas

I = I0(e^(eV/kT) – 1)

Step-by-Step Solution

eV/kT = (1.6e-19 x 0.5)/(1.38e-23 x 300) = 19.3. I = I0(e^19.3 – 1) = 0.01 x 2.4e8 = 2.4e6 A (ideal). Real diode limited by series resistance.

Final Answer

I = I0*e^(eV/kT) – ideal value very large; resistance limits actual current

Tips and Tricks

At forward bias the exponential dominates; series resistance limits real current.

Common Mistakes

Always use SI units. Check energy conservation accounts for all forms.