4) The voltage V across a capacitor at t seconds is given by the following table. Use the principle of least squares to fit a curve of the form V = get to the data: t (sec) V (volts) 0 150 2 63 4 28 6 12 8 5.6

3. For the circuit, (i) Find the voltage vc and the current ic if the capacitor was initially uncharged and the switch is thrown into position A. (ii) Find the voltage vc and the current ic if the switch is thrown into position B. (iii) Plot the waveforms for the questions (i) and (ii) for both the voltage vc and the current ic. Mark the time constant for part (i) and part (ii) in the waveforms with the corresponding values for current and voltage. A ww ic 20 kΩ B + + 12 V Vc. R, •10 kΩ 0.05 μF

the capacitor

1. The capacitor charges toward the source voltage through the resistor. The flash turns on when the capacitor voltage reaches 8 V. If C = 10 μF, find R such that the flash will turn on once per second.   2. Find the differential equation for the current in the circuit shown below.