If both the resistance and the inductance in an LR AC series circuit are doubled the new impedance will be
If both the resistance and the inductance in an LR AC series circuit are doubled the new impedance will be
A. halved
B. fourfold
C. doubled
D. quadrupted
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Correct Answer - C
For L-R circuit, `Z = sqrt(R^(2)+L^(2))`
Hence, `Z_(1) = sqrt(R^(2)+X_(L)^(2))`
Here, `Z_(1) = sqrt((R_(1)^(2)) + (X_(L_(2)))^(2))`
and `Z_(2) = sqrt((R_(2))^(2) + (X_(L2))^(2))`
Given, `R_(2)` = 2R and `X_(L2)= 2X_(L)`
`Z_(2) = sqrt((2r)^(2)+(2X_(L))^(2) = 2Z_(1)`
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