The amplification factor of a triode is 50. If the grid potential is decreased by 0.20 V, what increase, in plate potential will keep the plate current unchanged ?

Options

A. 5 V
B. 10 V
C. 0.2 V
D. 50 V

Answer

To solve the problem step by step, we will use the concept of the amplification factor (μ) of a triode. Here’s how we can approach it:

### Step-by-Step Solution:

1. **Understand the Given Values:**
- The amplification factor (μ) of the triode is given as 50.
- The decrease in grid potential (ΔVg) is given as -0.20 V (since it is a decrease).

2. **Recall the Formula for Amplification Factor:**
- The amplification factor (μ) is defined as:
\[ \mu = \frac{\Delta V_p}{\Delta V_g} \]
where:
- ΔVp = change in plate potential
- ΔVg = change in grid potential

3. **Rearranging the Formula:**
- To find the change in plate potential (ΔVp), we can rearrange the formula:
\[ \Delta V_p = \mu \times \Delta V_g \]

4. **Substituting the Values:**
- Now, substitute the known values into the equation:
\[ \Delta V_p = 50 \times (-0.20 \, \text{V}) \]

5. **Calculating ΔVp:**
- Perform the multiplication:
\[ \Delta V_p = 50 \times -0.20 = -10 \, \text{V} \]
- Since we are looking for an increase in plate potential to keep the plate current unchanged, we take the absolute value:
\[ \Delta V_p = 10 \, \text{V} \]

6. **Conclusion:**
- Therefore, the increase in plate potential required to keep the plate current unchanged is **10 V**.

### Final Answer:
The increase in plate potential required is **10 V**.

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