Q. Power dissipated in an LCR series circuit connected to an a.c. source of emf ε is:
A) ε²√[R² + (Lω − 1/Cω)²]/R
B) ε²[R² + (Lω − 1/Cω)²]/R
C) ε²R/√[R² + (Lω − 1/Cω)²]
D) ε²R/[R² + (Lω − 1/Cω)²]
Explanation
[Solution from source] Average power P = εrms Irms cos φ with I = ε/Z and cos φ = R/Z, so P = ε²R/Z² = ε²R/[R² + (Lω − 1/Cω)²]. Using only one factor of Z (the square-root form) gives the wrong power. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.