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PhysicsEMI/ACSeries AC CircuitsMedium2 minPYQ_2014
PhysicsMediummultiple choice

At time t = 0, terminal A in the circuit shown in the figure is connected to B by a key and an alternating current It=I0cosωt , with I0=1A and ω=500  rad/s starts flowing in it with the initial direction shown in the figure. At t=7π6ω , the key is switched from B to D. Now onwards only A and D are connected. A total charge Q flows from the battery to charge the capacitor fully. If C=20 μF, R=10 Ω and the battery is ideal with of 50V, identify the correct statement(s).

Question diagram: At time t = 0, terminal A in the circuit shown in the figure

Options:(select one or more)

Answer:
C, D
Solution:

Given,I=I0cosωt, Peak or maximum current I0=1A           angular frequency,ω=500 rad s-1           capacitance C=20μF           resistanceR=10Ω          battery voltage V=50VIf q represent the charge on capacitor’s upper plate:
It=I0cos(ωt) 
qt=I0ωsinωt
Max chargeqmax=1A500Rads=2×10-3C
Charge of upper plate att=76ω
=I0ωsin7πω =-I02ω
When capacitor is fully charged then charge on upper plate=50v×20μf
=10×10-3C
Q=1×10-3-I02ω=2×10-3C
Voltage across capacitor when A and D are connected=1×10-3C20×10-6μf=50V
Total voltage acrossR=100V
Current is anticlockwise

Stream:JEE_ADVSubject:PhysicsTopic:EMI/ACSubtopic:Series AC Circuits
2mℹ️ Source: PYQ_2014

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