IMPEDANCE of RL & RC Series AC Circuit | Physics 12 | Ch 20 ALTERNATING CURRENT | FBISE

📘 *IMPEDANCE of RL & RC Series AC Circuit | Physics 12 | Ch 20 Alternating Current | federal board | national book foundation*
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In this lecture, we explore the detailed concept of *Impedance* in *RL and RC Series AC Circuits* from *Chapter 20 – Alternating Current* of **Class 12 Physics (FBISE/NBF)**. This topic is essential for understanding how alternating current (AC) behaves in circuits containing **resistors (R)**, **inductors (L)**, and **capacitors (C)**.

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🎯 *Topics Covered:*
✔️ What is Impedance in AC circuits
✔️ Formula and unit of impedance
✔️ Phasor diagrams for RL and RC series circuits
✔️ RL Series Circuit – Current lag, voltage relationship, impedance triangle
✔️ RC Series Circuit – Current lead, voltage distribution, impedance triangle
✔️ Derivation of impedance: Z = √(R² + X²)
✔️ Reactance: Inductive (XL = 2πfL) & Capacitive (XC = 1 / 2πfC)
✔️ Example: Finding capacitive reactance and peak current
✔️ Assignment 20.2 solved – Expression for current through a capacitor

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📌 *Key Explanations:*

🔷 *Impedance (Z):*
Impedance is the total opposition to the flow of AC current in a circuit, combining both resistance (R) and reactance (X). Measured in ohms (Ω), it is given by the formula:
*Z = √(R² + X²)*

🔷 *RL Series Circuit:*
Current lags the voltage
Voltage drop across resistor is in phase with current
Voltage drop across inductor leads the current by 90°
Impedance triangle: sides R, XL, and Z
*Z = √(R² + XL²)*

🔷 *RC Series Circuit:*
Current leads the voltage
Voltage drop across resistor is in phase with current
Voltage drop across capacitor lags behind current by 90°
*Z = √(R² + XC²)*

🔷 *Capacitive and Inductive Reactance:*
*XL = 2πfL* (Inductive Reactance)
*XC = 1 / 2πfC* (Capacitive Reactance)

🔷 *Applications:*
Understanding impedance is crucial in designing filters, oscillators, communication devices, and audio systems.

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🧪 *Solved Example (20.2):*
Given: V = 16 sin(2×10³t) across a 0.5 μF capacitor
✔️ Find: (a) Capacitive reactance (XC)
✔️ (b) Peak current (I₀)

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📺 *Instructor:* Sir Anjum
📝 *Textbook Reference:* Physics Class 12 | Chapter 20 | Alternating Current | National Book Foundation (NBF)

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🔖 *Hashtags:*
#impedance #RLcircuit #RCcircuit #physics12 #alternatingcurrent #fbisephysics #nbfbook #reactance #phasordiagram #acphysics #siranjumteaches #physicslecture #capacitivereactance #inductivereactance

🎯 **Tags **
Impedance in AC circuit, RL series circuit, RC series circuit, Physics class 12 chapter 20, AC impedance, Impedance triangle, Capacitive reactance, Inductive reactance, AC phasor diagram, Federal board physics, NBF physics textbook, Alternating current impedance, Peak current in capacitor, Impedance formula, Class 12 Physics FBISE, AC circuit analysis, AC voltage, RLC circuit explanation, Sir Anjum Physics, Matric Physics 2nd year

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