When the voltage drop across a `p.n` junction diode is increased from `0.65V` to `0.70V`, the change in the diode current is `5mA`. What is the dynamic resistance of the diode?

Options

A. `5 Omega`
B. `10 Omega`
C. `20 Omega`
D. `25 Omega`

Explanation

To find the dynamic resistance of the diode, we can use the formula for dynamic resistance \( r_d \):

\[ r_d = \frac{\Delta V}{\Delta I} \]

where:
- \( \Delta V \) is the change in voltage across the diode,
- \( \Delta I \) is the change in current through the diode.

### Step 1: Identify the change in current (\( \Delta I \))
The change in current is given as \( 5 \, \text{mA} \). We need to convert this to amperes:

\[ \Delta I = 5 \, \text{mA} = 5 \times 10^{-3} \, \text{A} \]

### Step 2: Calculate the change in voltage (\( \Delta V \))
The voltage drop across the diode changes from \( 0.65 \, \text{V} \) to \( 0.70 \, \text{V} \). Therefore, the change in voltage is:

\[ \Delta V = 0.70 \, \text{V} - 0.65 \, \text{V} = 0.05 \, \text{V} \]

### Step 3: Substitute the values into the dynamic resistance formula
Now, we can substitute the values of \( \Delta V \) and \( \Delta I \) into the formula for dynamic resistance:

\[ r_d = \frac{\Delta V}{\Delta I} = \frac{0.05 \, \text{V}}{5 \times 10^{-3} \, \text{A}} \]

### Step 4: Calculate the dynamic resistance
Now, perform the calculation:

\[ r_d = \frac{0.05}{5 \times 10^{-3}} = \frac{0.05}{0.005} = 10 \, \Omega \]

### Final Answer
The dynamic resistance of the diode is \( 10 \, \Omega \).

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