In rc circuit, long after switch is closed current through the capacitor will be
a. increase
b. remain the same
c. zero
d. none of the above

C. Zero.

Explanation:

A Resistor and Capacitor combination is called an RC circuit.

When the switch is closed, the charge  on the capacitor starts to increase. This continues until the voltage across it becomes the supply voltage provided by the battery. (EMF of the battery).  Current is maximum.

As charge builds up on the capacitor, current will slow down. Once the capacitor is fully charged, no more current flows in the circuit, since the capacitor behaves as an open circuit.

The voltage increase provided by the battery is equal tot he voltage drop across the capacitor . At this point, the voltage drop across the resistor is zero and hence No Current flows.

As time increases, the current across it decreases exponentially according to the equation I (t) = I(0) e ⁻ t / τ .

hi there!

out of the two, (b) precision would be more reasonable.   however, both a and b could be pretty reasonable.

-awesomerepublic   : )