f=1/T

看上一个点的位置

电场,磁场都产生横波,两者产生的波相互垂直

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e.m.f.:the amount of energy supplied by the cell to each unit of charge.

p.d:energy transferred per unit of charge.

Ohm's law:providede the tempurature and other physical factors remain constant,the current through a wire is proportional to the potential difference actoss its ends.

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