Alternating Current notes
OpenThe 4 formulas you need for Alternating Current, on one page.
For explanations and lectures, see the full topic page. Then test yourself with 5 JEE Main 2026 PYQs.
Physics · printable
Alternating Current: One-Page Formula Sheet
Print it or save it as a PDF. It fits on one page.
Last updated: 26 October 2026
Formula sheet
Alternating Current formulas
Alternating Current — formula sheet
Formulas
- V_rms = V₀/√2
- X_L = ωL, X_C = 1/ωC, Z = √(R² + (X_L − X_C)²)
- Resonance ω₀ = 1/√(LC); Q = ω₀L/R
- P_avg = V_rms I_rms cosφ
Key ideas
- In a pure inductor current lags voltage by 90°; in a capacitor it leads by 90°
- At resonance X_L = X_C and impedance is minimum
- Average power uses the power factor cosφ
- An ideal transformer conserves power
Traps to avoid
- Adding R, X_L and X_C directly
- Using peak instead of RMS values for power
- Forgetting the power factor is R/Z
jeevisionary.in/jee-topics/physics/alternating-current/
FAQs
Frequently asked questions
Where can I get a Alternating Current formula sheet PDF for free?
On this page. Use the print button and choose 'Save as PDF'.
How should I use a formula sheet?
Read it once a day for a week, then cover it and write the formulas from memory. Revise only the ones you missed.