Energy of inductior 高手幫幫手~

2010-12-11 1:00 am

Energy of inductor = 1/2 Li^2, where L is the inductance and i is the current.

我不明白這條式
因為induced emf = L di/dt, 如果current是constant, 應該沒有induced emf, 即是話個inductor可以當它是一條wire。但跟E=1/2 L i^2, 在current是constant時還會有energy stored as magnetic field?

回答 (1)

天同

2010-12-12 12:59 am

✔ 最佳答案

Induced emf and energy are two different physical parameters. The former is because of a change of current with time, whereas the latter is due to the presence of magnetic field produced by a current.

When the current first builds up, there is an increase of current with time, hence an induced back emf is produced. Energy needs to be supplied (from the power source, like a battery) to counter-balance the back emf. This energy is eventually stored in the magentic field produced by the current. The energy supplied to the inductor, hence the energy stored in the magnetic field, at the instant when the current reaches a value of i is thus given by (1/2)L.i^2.

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