54. For the circuit in the figure below, four capacitors of capacitances 0.5 µF,1.5 µF, 2 µF and 4 µF are used. B is a bulb of unknown resistance R. 5 ma(a) Calculate the equivalent capacitance of the 4 capacitors. (b) Knowing that the time constant of the circuit is 12 ms, calculate the resistance of the bulb.(5 mo (c) At t = 0, an ideal battery delivering 12 V is connected between nodes a and b. Calculate how long after connecting the battery the current through the bulb reaches 1 mA. (d) Calculate the energy stored on all capacitors when the currentthrough the bulb is 1 mA. (e) Calculate the energy dissipated on the bulb and the total charge stored in the capacitors a long period of time after connecting the battery.

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