A coil of negligible resistance is connected inseries with `90 Omega` resistor acorss a 120 V -60 Hz line. A voltmeter reads 36 V across the resistance. Find voltage across the coil and inductance of the coil.

Explanation

Here, `R = 90 Omega, V = E_(v) = 120 V`,
`v = 60 Hz. , V_(r ) = 36 V, V_(L) = ? L = ?`
As `V_(R ) = I R :. I = (V_(R ))/(R ) = (36)/(90) = 0.4 A`
As `V^(2) + V_(L)^(2)`
`:. V_(L) = sqrt(V^(2) - V_(R )^(2)) = sqrt(120^(2) - 36^(2) ) = 114.5 V`
As `V_(L) = IX_(L) :. X_(L) = (V_(L))/(I) = (114.5)/(0.4) = 286.2 Omega`
As `X_(L) = 2 pi v L`
`:. L = (X_(L))/(2 pi v) = (286.2)/(2(3.14)60) = 0.76 H`