JEE Mains · Physics · STD 12 -7. Alternating current
A series \(LR\) circuit connected with an ac source \(E=(25 \sin 1000 t)\ V\) has a power factor of \(\frac{1}{\sqrt{2}}\). If the source of emf is changed to \(E=(20 \sin 2000 t)\ V,\) the new power factor of the circuit will be _______.
- A \(\frac{1}{\sqrt{2}}\)
- B \(\frac{1}{\sqrt{3}}\)
- C \(\frac{1}{\sqrt{5}}\)
- D \(\frac{1}{\sqrt{7}}\)
Answer & Solution
Correct Answer
(C) \(\frac{1}{\sqrt{5}}\)
Step-by-step Solution
Detailed explanation
\( E=25 \sin (1000 t) \) \( \cos \theta=\frac{1}{\sqrt{2}}\) LR circuit \( \text { Initially } \frac{R}{\omega_1 L}=\frac{1}{\tan \theta}=\frac{1}{\tan 45^{\circ}}= \) \( X_L=\omega_1 L \) \( \omega_2=2 \omega_1 \text {, given } \)…
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