Each capacitor shown in the figure has a capacitance of 5.0 μF. The emf of the battery is 50V. How much charge will flow through AB if the switch S is closed?


Given :


Capacitance C= 5.0 μF


Voltage V= 50V


Formula used :


1) If switch S is closed, it will be a short circuit. Current flow always chooses a low resistance path. No current will flow through capacitor at switch S., So we don’t need to consider it. Finally, we will left with two capacitor which are in parallel. We add the capacitance when the capacitors are in parallel.


Ceqv=C1+C2


Where


C1, C2 are the capacitance of the capacitors


2) Charge supplied by the battery



Where


C is the capacitance of the capacitor


V is the voltage across the capacitance


Q is the charge on the capacitor


Putting the values in the formula 1, we get


Ceqv= 5+5=10μF


Putting the values in the formula 1, we get



Charge supplied by the battery Q=500μC.


But when the switch has not connected the charge Q=Ceq×V


The capacitors are connected in series connection, we get




After switch S is closed the initial charge stored in the capacitor will discharge.


Note: Q1 will be negative because the capacitor is discharging.)


So the net charge flows from A to B is


Total Charge will flow through A and B when switch S is closed.


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