posted by derek on .
Two parallel plate capacitors are identical, except that one of them is empty and the other contains a material with a dielectric constant of 4.2 in the space between the plates. The empty capacitor is connected between the terminals of an ac generator that has a fixed frequency and rms voltage. The generator delivers a current of 0.23 A. What current does the generator deliver after the other capacitor is connected in parallel with the first one?
Vm = Xc Im
Xc = 1/ωC
therefore for fixed V
I2/I1 = C2 /C1
C2 = 4.2C1 + C1 = 5.2C1 (they are connected in parallel)
I2 = (C2/C1)I1 = 5.2*0.22 = 1.144 A