| Directions: In the following questions, a statement of Assertion [A] is followed by a statement of Reason (R). |
| Mark the correct choice as: |
| Assertion [A]: At resonance, LCR series circuit have a maximum current. |
| Reason (R): At resonance, in LCR series circuit, the current and e.m.f. are in phase with each other. |
A) Both Assertion [A] and Reason (R) are true and Reason (R) is the correct explanation of Assertion [A]
B) Both Assertion [A] and Reason (R) are true but Reason (R) is not the correct explanation of Assertion [A]
C) Assertion [A] is true but Reason (R) is false
D) Assertion [A] is false and Reason (R) is also false
Correct Answer: B
Solution :
(b) At resonance, \[{{X}_{L}}={{X}_{C}}\] or \[\omega L=\frac{1}{\omega C}\]. Because of this impedance of LCR series circuit become equal to resistance of circuit \[(Z=\sqrt{{{R}^{2}}+{{\left( {{X}_{L}}-{{X}_{C}} \right)}^{2}})}\]. Therefore from \[l=\frac{E}{Z}=\frac{E}{R}\], at resonance, current in LCR series circuit is maximum. Correspondingly phase angle is also equal to zero. Therefore emf and current are in phase in LCR series circuit.
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