Question

A 45-mH inductor is connected to an ac source of emf with a frequency of 250 Hz and a maximum emf of 20 V. If the voltage across the inductor is +20 V at time t = 0, what is the voltage at time t = 2.0 ms?

• A : 0 V      

• B : −10 V      

• C :20 V    

• D : −20 V    

• E : 10 V

Answer 1

Solution given L=HSMH, ¥ -250 Hz ,Vo= 2oV Led Vollerge across inducter is V at tim V= V. Sin(eut t ) V= 20 Sin ( 17X2x+) t= 2 ms ) =20 Sin (x+) Vi - 20 Sin ( sooX 25x V, =- 20 Voff Vi =-20 V Ans D: -20 V