In the connection shown in the figure, initially the switch K is open and the capacitor is uncharged. Then the switch is closed, and the capacitor is charged up to the steady state and the switch is opened again. Determine the values indicated by the values indicated by the ammeter.
`[Given V_0 = 30 V, R_1 = 10k Omega, R_2 = 5kOmega`]
.
just after closing the switch

Options

A. 2mA
B. 3 mA
C. 0 mA
D. none of these

Answer

C

Explanation

c. Just after closing, capacitor behaves as short circuit and all current flows
through it, hence ammeter reads zero.
After a long time, capacitor behaves as an open circuit and no current
flows through it. Therefore,
`i = v_0/(R_1+R_2) = 30/(10+5) = 2mA`
Just after reopening, potential difference across `R_2` remains the same
initially as charge on capacitor does not charge initially. Hence,
current remains the same.