Consider a circuit with Resistance, Inductor and Capacitor connected in series. The phase difference between the current and the alternating voltage (at resonance) is: 

Concept:

LCR circuit stands for inductance-capacitance-resistance. LCR circuits are also used to change the impedance of the circuit, and to increase or decrease the resistance of the current of different frequencies present in it. All these uses can be used individually or they can be used all together to get the wanted results in an electronic device.

From the phasor diagram, 

\(V_R=IR\)

\(V_L=IX_L\)

\(V_C=IX_C\)

\(I=\frac{V}{\sqrt{R^2+(X_L-X_C)^2}}\)

Impedance \(Z={\sqrt{R^2+(X_L-X_C)^2}}\)

As an LCR circuit can only work when it is connected in a series pattern, therefore, the LCR series circuit is almost similar to a series electrical circuit. The only difference between both these is that a series electric circuit current stays the same throughout the circuit but in an LCR set-up, we can regulate the flow of current and can also restrict it from flowing to other components. At resonance frequency, the impedance in LCR series circuit is minimum. 

In series LCR circuit, \(X_L=X_C\)

\(\implies V=IR\)

In series LCR circuit, phase angle is given as \(tan\phi=\frac{X_L-X_C}{R}\)

\(tan\phi=0\implies\phi=0^o\)

• When the inductive reactance \(X_L\)  is equal to the capacitive reactance \(X_C\) , the tangent of the phase angle (θ) is zero, indicating that the voltage is in phase with the current. This type of circuit is known as a resonant circuit.

Hence, the correct answer is Option-2-\(\phi=0^o\).