RC Circuit 90° Phase Trick 🔥 | Find Frequency Fast
❓ Question Given: R = 100 kΩ C = 100 pF Phase difference between: V i n and ( V B − V A ) V_{in} \quad \text{and} \quad (V_B - V_A) is 90°. Input signal frequency: ω = 10 x rad/s \omega = 10^x \text{ rad/s} Find x . 🖼 Question Image ✍️ Short Concept In an RC circuit: Capacitive reactance: X C = 1 ω C X_C = \frac{1}{\omega C} 90° phase condition usually occurs when: X C = R X_C = R 👉 That means: ω = 1 R C \omega = \frac{1}{RC} 🔷 Step 1 — Write Key Relation 💯 For 90° phase condition: ω = 1 R C \boxed{\omega = \frac{1}{RC}} This is the MOST IMPORTANT step. 🔷 Step 2 — Convert Values R = 100 kΩ = 10 5 Ω = 10^5 \, \Omega C = 100 pF = 10 − 10 F = 10^{-10} \, F 🔷 Step 3 — Calculate RC R C = 10 5 × 10 − 10 RC = 10^5 \times 10^{-10} R C = 10 − 5 RC = 10^{-5} 🔷 Step 4 — Find Angular Frequency ω = 1 R C \omega = \frac{1}{RC} = 1 10 − 5 = \frac{1}{10^{-5}} = 10 5 rad/s = 10^5 \text{ rad/s} So, x = 5 x = 5 ✅ Final Answer x = 5 \boxed{x = 5...