I have no idea what to do with this problem, if you can hel p me out, I'd appreciate it!
At a given instant an 62 mH inductor stored an energy of 81 µJ.
What is the current in the inductor at this instant?
___________ mA
If the current is increasing at the rate of 95 mA/s, how long does it take for the energy to increase by a factor of 51 from the initial value?
_______________ s
Please show me the work done so I understand what equations you're using and how to utilize them in other problems. Much appreicated!
Angel Mina
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Answers & Comments
Verified answer
1) for an inductor, the energy stored is U = (1/2) L i^2, where 'i' is the current value.
then, 81x10^-6 = (1/2) x 62x10^-3 i^2 or i^2 = 2x81x10^-6 / 62x10^-3 = 26.13 x10^-4
or i = 5.11x10^-2 amp = 51.1x10^-3 amp = 51.1 mA
2) since U = (1/2) L i^2 then, U / t^2 = (1/2) L (i/t)^2
ie., t^2 = 2 U / L (1/t)^2 = 2x65.61x10^-6 / 62x10^-3 x (95x10^-3)^2 = 131220 / 559550= 0.2345
ie., time t= 0.484 sec = 0.5 sec (nearly)
Quite simple!
Energy stored in an inductor=0.5 LI²
Given, L=62mH=62*10^-3 Henry and
Energy E stored= 81*10^-6 J
which gives 81*10^-6=0.5*62*10^-3*I²
or I â 0.05112 A â 51.12 mA