For an LCR circuit driven at frequency ω, the equation reads
(i) Multiply the equation by i and simplify where possible.
(ii) Interpret each term physically.
(iii) Cast the equation in the form of a conservation of energy statement.
(iv) Integrate the equation over one cycle to find that the phase difference between v and i must be acute.
Given:
Equation given : 
(i)
Multiplying the equation by I,
Multiplying by (1/2) and substituting i=dq/dt
Hence, the simplified equation.
(ii)
Here, first term: 
means the rate of change of energy stored in the inductor.
Second term : 
represents the Joule’s Heating Loss.
Third Term: 
Represents rate of change of energy in Capacitor.
Fourth term: 
represents the energy due to driving force. It increases stored energy in inductor and capacitor.
(iii)
Conservation of Energy states that:
The sum of the individual energies across the individual components is equal to the total power of the circuit.
The equation in the form of a conservation of energy statement is
(iv)
Integrating the equation from 0 to T with resected to dt.
The integral of first term and third term would be zero as d/dt and dt gets cancelled. and V=Vmsinωt
LHS is positive as i, R and T are always positive, hence RHS is also positive.
Hence, phase difference between v and I must be acute for the cycle to be positive.