Question

A diode is forward biased by 0.7 V. If the forward resistance is 10 $\Omega$, the current through the diode is:

• A. 0.007 A
• B. 0.07 A
• C. 0.7 A
• D. 7 A

Hint:

A simple application of Ohm's Law ($I = V/R$) is sufficient here.
Always pay attention to units: $0.7 / 10 = 0.07\text{ A}$ (or $70\text{ mA}$).
In exams, make sure you do not misplace the decimal point.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
This question is from "Semiconductor Electronics," focusing on the electrical characteristics of a semiconductor diode in its forward-biased state.
We are given the voltage across the diode and its forward resistance, and we need to find the resulting current.

Step 2: Key Formula or Approach:
For a diode operating in the forward-bias region, we can determine the current ($I$) flowing through it using Ohm's Law:
\[ I = \frac{V}{R_f} \]
where $V$ is the forward bias voltage across the diode, and $R_f$ is the forward resistance of the diode.

Step 3: Detailed Explanation:

• We are given the following parameters:
Forward bias voltage ($V$) = $0.7\text{ V}$
Forward resistance ($R_f$) = $10\ \Omega$

• Substituting these values into the Ohm's law formula:
\[ I = \frac{0.7\text{ V}}{10\ \Omega} \]

• Performing the division:
\[ I = 0.07\text{ A} \]

• In a real silicon $p$-$n$ junction diode, the barrier potential is approximately $0.7\text{ V}$.

• When the forward voltage reaches this value, the depletion region narrows significantly, allowing current to flow easily, limited only by the dynamic resistance of the semiconductor.



Step 4: Final Answer:
The current through the diode is $0.07\text{ A}$, which corresponds to option (B).