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How does the sign of the phase angle phi...

How does the sign of the phase angle `phi`, by which the supply voltage leads the current in an LCR serices circuit, change as the supply frequency is gradually increased from very low to very high values ?

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The supply voltage leads the current in LCR series circuit by `/_ phi` , where
`tan phi = (X_(L) - X_(C ))/(R ) = (2 pi v L - 1//2 pi v C)/(R )`
When v is low, `tan phi` is negative ,`phi` is negative.
When `v = v_(r) , 2 pi v L = 1//2 pi v C, tan phi = 0 , phi = 0^(@)`.
When `v gt v_(r) , tan phi` is positive , `phi` is positive.
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