Skip to main content
Super TutorResources
Chapter 18 of 29
QuestionsNotesFlashcardsSummaryFormulasQuizConceptsSyllabusPlan
Revision Notes

Alternating Currents

Telangana Open School (TOSS) · Class 12 · Physics

Quick revision notes for Alternating Currents — Telangana Open School (TOSS) Class 12 Physics. Key concepts, formulas, and definitions for last-minute revision.

51 questions30 flashcards5 concepts

Interactive on Super Tutor

Studying Alternating Currents? Get the full interactive chapter.

Quizzes, flashcards, AI doubt-solver and a step-by-step study plan — built for revision notes and more.

Try Super Tutor — Free

1,000+ Class 12 students started this chapter today

Key Topics to Revise

1

Alternating Current and Voltage

  • AC voltage and current vary sinusoidally with time.
  • General equations: \( V = V_m \cos \omega t \) and \( I = I_m \cos \omega t \).
  • Peak values: \( V_m \) and \( I_m \) are maximum voltage and current.
2

AC in Resistive, Inductive, and Capacitive Circuits

  • In a pure resistor, voltage and current are in phase (phase difference = 0).
  • In a pure inductor, current lags voltage by \( 90^\circ \) or \( \pi/2 \) radians.
  • In a pure capacitor, current leads voltage by \( 90^\circ \) or \( \pi/2 \) radians.
3

Series LCR Circuit and Resonance

  • In a series LCR circuit, impedance \( Z = \sqrt{R^2 + (X_L - X_C)^2} \).
  • Current \( I_{\text{rms}} = \frac{V_{\text{rms}}}{Z} \).
  • Phase angle \( \phi \) is given by \( \tan\phi = \frac{X_L - X_C}{R} \).
4

Power in AC Circuits and Transformers

  • Average power \( P_{\text{av}} = V_{\text{rms}} I_{\text{rms}} \cos\phi \).
  • Power factor \( \cos\phi = \frac{R}{Z} \), ranges from 0 to 1.
  • In pure resistor, power factor = 1; in pure L or C, power factor = 0.

Get complete notes with diagrams and examples

Full Notes

Key Concepts

AC voltage and current vary sinusoidallyPhasors are rotating vectors usedCapacitive reactance $ X_C = 1/(\omegaAverage power in an AC circuitTransformers change AC voltage levels using

Frequently Asked Questions

What are the important topics in Alternating Currents for Telangana Open School (TOSS) Class 12 Physics?
Alternating Currents covers several key topics that are frequently asked in Telangana Open School (TOSS) Class 12 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Alternating Currents — Telangana Open School (TOSS) Class 12 Physics?
Understand the core concepts first, then work through the 51 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

More resources for Alternating Currents

All 29 chapters — Telangana Open School (TOSS) Class 12 Physics Revision Notes

For serious students

Get the full Alternating Currents chapter — for free.

Quizzes, flashcards, AI doubt-solver and a step-by-step study plan for Telangana Open School (TOSS) Class 12 Physics.

Try Super Tutor Free
Try the full chapter — Free