Draw the approcimate vector diagrams of currents in the circuits shown in figure. The voltage applied across the points `A` and `B` is assmed to be sinosoidal`,` the parameters of each circuit are so chosen that the total current `I_(0)` lags in phase behind the external voltage by an angle `varphi`.

Explanation

`(a)` For the resistance, the voltage and the current are in phase. For the coil the voltage is ahead of the current by less than `90^(@)`. The current is obtained by addiction because the elements are in parallel.
`(b)` `I_(C)` is ahead of the voltage by `90^(@)`.
`(b)` The coil has no resistance so `I_(L)` is `90^(@)` behind the voltage.
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