Resonance of series LRC circuit ECT & Ioe Regular VVI Question for ECT Question no1

 Resonance of series LRC circuit VVI Question ECT | IOE Exam Regular

From figure 1. Voltage across each component of circuit

Applying KVL in circuit

Thus, we see that magnitude of current depends upon the frequency.

The inductive reactance is given by:-

At higher frequency XC is low and XL is high as at lower frequency XC is increased and XL is decreased. But there will be a frequency at which XL=XC this frequency is known as resonance frequency.

Conclusions: 

• 1. XL=XC 
• 2. Impedance of the circuit is minimum i.e. Z=R 
• 3. Current flowing in circuit will be maximum. i.e I=V/R 
• 4. Voltage across Xc will be equal to XL but 180 out of phase which cancel out each other. 
• 5. power factor is unity. i.e. pf = 1 
• 6. phase angle between voltage and current will be equal to zero. 
• 7. circuit behaves like purely resistive circuit. 
• 8. Total supply voltage will be appear at resistor. i.e.V=VR