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A coil of inductance 1.0 H and resistance 100 Omega is connected to a battery of emf 12 V. Find the energy stored in the magnetic field associated with the coil at an instant 10 ms after the circuit is switched on. |
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Answer» Time constant of circuiti is `tau = (L)/(R ) =(1.0)/(100) = 10^(-2)s` As `I = I_(0) (1 - e^(-t//tau)) = (E _(0))/(R ) (1 - e^(-t//tau`) `:. I = (12)/(100) (1 - e^(-10^(-2_(//10^(-2)))))` ` = 0.12 (1 - (1)/(e)) = 0.0758 A` Energy store `= (1)/(2) LI^(2) = (1)/(2) xx 1.0 (0.0758)^(2)` `= 2.87 xx 10^(-3) J` Maximum electric intnesity the capacitor can withstand = 10% dielectric strength i.e., `E = (10)/(100) xx 3.0 xx 10^(6) = 3 xx 10^(5) V//,` `d = 1 mm = 10^(-3) m` |
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