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In ac circuit contains a pure capacitor,...

In ac circuit contains a pure capacitor, across which an ac emf
`e = 100 sin (1000t)`, volt
is applied. If the peak value of the current is 200 mA, then the value of the capacitor is

A

`2mu`

B

`20 muF`

C

`5 muF`

D

`500 muF`

Text Solution

AI Generated Solution

The correct Answer is:
To find the value of the capacitor in the given AC circuit, we can follow these steps: ### Step-by-step Solution: 1. **Identify the given parameters:** - The AC voltage is given as \( e = 100 \sin(1000t) \) volts. - The peak current \( I_0 = 200 \, \text{mA} = 200 \times 10^{-3} \, \text{A} = 0.2 \, \text{A} \). 2. **Calculate the peak voltage \( V_0 \):** - The peak voltage \( V_0 \) from the given equation is \( 100 \, \text{V} \). 3. **Determine the capacitive reactance \( X_C \):** - The relationship between peak voltage and peak current in a capacitor is given by: \[ X_C = \frac{V_0}{I_0} \] - Substituting the values: \[ X_C = \frac{100}{0.2} = 500 \, \Omega \] 4. **Use the formula for capacitive reactance:** - The capacitive reactance \( X_C \) is also given by: \[ X_C = \frac{1}{\omega C} \] - Where \( \omega \) is the angular frequency. From the voltage equation, we have \( \omega = 1000 \, \text{rad/s} \). 5. **Set the two expressions for \( X_C \) equal to each other:** \[ 500 = \frac{1}{1000 C} \] 6. **Solve for the capacitance \( C \):** - Rearranging the equation gives: \[ C = \frac{1}{500 \times 1000} \] - Calculating this yields: \[ C = \frac{1}{500000} = 2 \times 10^{-6} \, \text{F} = 2 \, \mu\text{F} \] 7. **Conclusion:** - The value of the capacitor is \( 2 \, \mu\text{F} \). ### Final Answer: The value of the capacitor is \( 2 \, \mu\text{F} \). ---
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