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If the frequency of the ac. circuit illustrated above is 500/π Hz what would be the reactance in the circuit? 

(Inductance (L) = 0.9H, Capacitance (C) = \(2 \times 10^{-6}\)

A.

0.0009Ω/π

B.

100Ω

C.

1030Ω

D.

400Ω

E.

2500Ω

Correct answer is D

Given Data: Frequency (F) = \(\frac{500}{π}\) , Inductance (L) = 0.9H, Capacitance (C) = \(2 \times 10^{-6}\)

Total circuit reactance = Inductive reactance ( X\(_L\) ) - Capacitive reactance ( X\(_C\) )

when  ( X\(_L\) ) >  ( X\(_C\) )

Inductive reactance ( X\(_L\) ) = 2πFL = 2 \(\times\) π \(\times\) \(\frac{500}{π}\) \(\times\) 0.9 = 900Ω

Capacitive reactance ( X\(_C\) ) = \(\frac{1}{2πFC}\) = \(\frac{1}{2 \times π \times 500/π \times 2 \times 10^{-6}}\)

= \(\frac{1}{2 \times 10^{-3}}\) = \(\frac{1}{0.002}\)  

= 500Ω

 

Total circuit reactance =  ( X\(_L\) ) -  ( X\(_C\) ) = (900 - 500)Ω

=400Ω