A capacitor acts as an infinite resistance for

Options

A. DC
B. AC
C. DC as well as AC
D. Neither AC nor DC

Answer

To solve the question "A capacitor acts as an infinite resistance for", we need to analyze the behavior of a capacitor in different types of current: Direct Current (DC) and Alternating Current (AC).

### Step-by-Step Solution:

1. **Understanding Capacitive Reactance**:
- The capacitive reactance (Xc) of a capacitor is given by the formula:
\[ X_c = \frac{1}{\omega C} \]
- Here, \( \omega \) is the angular frequency, and \( C \) is the capacitance of the capacitor.

2. **Frequency in AC and DC**:
- For AC (Alternating Current), the frequency (\( \nu \)) is non-zero. Therefore, \( \omega = 2 \pi \nu \) is also non-zero.
- For DC (Direct Current), the frequency is zero because the current does not alternate or change over time.

3. **Evaluating Capacitive Reactance for AC**:
- Since the frequency is non-zero for AC, the capacitive reactance \( X_c \) can be calculated as:
\[ X_c = \frac{1}{\omega C} \quad (\text{where } \omega \neq 0) \]
- This means \( X_c \) will have a finite value and will not be infinite.

4. **Evaluating Capacitive Reactance for DC**:
- For DC, since the frequency is zero, we have:
\[ X_c = \frac{1}{0} \quad (\text{as } \omega = 0) \]
- This implies that \( X_c \) approaches infinity, indicating that the capacitor acts as an infinite resistance.

5. **Conclusion**:
- From the analysis, we conclude that a capacitor acts as an infinite resistance for DC and not for AC.

### Final Answer:
The correct option is that a capacitor acts as an infinite resistance for **DC**.

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