The change in current through a junction diode is \[1.2mA\] when forward bias voltage is changed by \[0.6V\]. The dynamic resistance is

A. 500Ω

B. 300Ω

C. 150Ω

D. 250Ω

To find the dynamic resistance of the junction diode, we can use the relationship between the change in voltage and the change in current. The dynamic resistance (r_d) can be calculated using Ohm's Law, which states that resistance is equal to the change in voltage divided by the change in current. In this case, we have a change in voltage (ΔV) of 0.6V and a change in current (ΔI) of 1.2mA. Let's break this down step by step.

Calculating Dynamic Resistance

The formula for dynamic resistance is:

r_d = ΔV / ΔI

Step 1: Convert Units

First, we need to ensure that the current is in the correct unit. Since 1.2mA is equal to 0.0012A, we can substitute this value into our formula.

Step 2: Substitute Values

Now, we can plug in the values:

r_d = 0.6V / 0.0012A

Step 3: Perform the Calculation

Now, let's do the math:

r_d = 0.6 / 0.0012 = 500Ω

Conclusion

The dynamic resistance of the junction diode is 500Ω. Therefore, the correct answer is A. 500Ω.

Understanding the Concept

Dynamic resistance is an important concept in electronics, particularly for diodes and transistors. It reflects how the current through a device changes in response to small changes in voltage. In practical terms, this means that if you increase the voltage slightly, the current will change, and the dynamic resistance gives you an idea of how much current will change for a given voltage change.

In this case, a small increase in voltage (0.6V) resulted in a relatively small increase in current (1.2mA), leading to a dynamic resistance of 500Ω. This information can be crucial when designing circuits, as it helps predict how components will behave under different conditions.