Class 12 Physics
CBSE and UP Board
Alternating Current
Chapter-7 Exercise 7.8
NCERT Solutions for Class 12 Physics Chapter 7 Question 8
Suppose the initial charge on the capacitor in Exercise 7.7 is 6 mC. What is the total energy stored in the circuit initially? What is the total energy at later time?
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Capacitance of the capacitor, C = 30μF = 30 x 10⁻6F
Inductance of the inductor, L = 27 mH = 27 x 10⁻3 H
Charge on the capacitor, Q = 6 mC = 6 x 10⁻3 C
Total energy stored in the capacitor can be calculated as:
E = 1/2 x Q2/C = 1/2 x (6 x 10⁻3)2/(30 x 10⁻6) = 6/10 = 0.6 J
Total energy at a later time will remain the same because energy is shared between the capacitor and the inductor.