Question:
In \(AC\) circuit with source voltage \(E \) = \(20\) \(sin\; 1000 \;t\) is connected to series \(L-R\) circuit whose power factor is \(\frac{1}{\sqrt 2}\) If \(E = 25\) \(sin \;2000\) \(t\), the new power factor is :
In \(AC\) circuit with source voltage \(E \) = \(20\) \(sin\; 1000 \;t\) is connected to series \(L-R\) circuit whose power factor is \(\frac{1}{\sqrt 2}\) If \(E = 25\) \(sin \;2000\) \(t\), the new power factor is :
Updated On: Apr 11, 2024
- \(\frac{2}{\sqrt5}\)
- \(\frac{1}{\sqrt5}\)
- \(\frac{1}{\sqrt3}\)
- \(\sqrt{(\frac{3}{5}})\)
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The Correct Option is B
Solution and Explanation
The Correct Option is (B) : \(\frac{1}{\sqrt5}\)
Old : 
New :
R = 1000 L
\(\cos\theta=\frac{R}{Z}\)
\(=\frac{1000L}{\sqrt{(1000L)^2+(2000L)^2}}\)
\(=\frac{1}{\sqrt{1+4}}\)
\(=\frac{1}{\sqrt5}\)
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Concepts Used:
AC Voltage
When voltage changes its direction after every half cycle is known as alternating voltage. The current flows in the circuit at that time are known as alternating current. The alternating current(AC) follows the sine function which changes its polarity concerning time. Most of the electrical devices are operating on the ac voltage.
