Tiwari Academy Discussion

Jay Ghosh

Asked: December 13, 2024In: Class 12 Physics

How much average power, over a complete cycle, does an a.c.source supply to a capacitor?

Zero, because current and voltage differ in phase by π/2 . Class 12 Physics Chapter 7 Alternating current Session 2024-2025.

Jay Ghosh

Asked: December 12, 2024In: Class 12 Physics

In a series LCR circuit, the voltage across an inductor, a capacitor and a resistor are 20 V, 20 V and 40 V, respectively, What is the phase difference between the applied voltage and the current in the circuit?

Zero, because V^l and Vc nulify each other and effectively the circuit is resistive in nature. Class 12 Physics Chapter 7 Alternating current Session 2024-2025.

Jay Ghosh

Asked: December 12, 2024In: Class 12 Physics

Difine capacitive reactance. write its SI units.

Capacitive reactance of a capacitor is the opposition offered by it for flow of a current through it. Capacitive reactance Xc = 1/Cw , where w is the angular frequency of current supply. SI unit of capacitive reactance is ohm ...

Jay Ghosh

Asked: December 12, 2024In: Class 12 Physics

Find the capacitance of the capacitor that would have a reactance of 100Ω when used with an a.c. source of frequency 5/π kHz.

Here Xc = 100Ω, v = 5/π kHz = 5000/π Hz ∴ C = 1/Xc . 2πv = 1/100 × 2π × 5000/π = 10-⁶F = 1µF. Class 12 Physics Chapter 7 Alternating current Session 2024-2025.

Jay Ghosh

Asked: December 12, 2024In: Class 12 Physics

A reactive element, in an a.c. circuit, causes the current flowing (i) to lag in phase by π/2 , (ii) to lead in phase by π/2 with respect to the applied voltage. Identify the element in each case.

(i) In an inductor current logs behaind the voltage by a phase angle of π/2 . (ii) In a capacitor current leads the voltage by a phase angle of π/2 . Class 12 Physics Chapter 7 Alternating current Session ...