115 + 10.4- 135 405 540 (? t(ms) TF We saw in class today that a 9 volt battery (containing 10 kJ) could power a simple LED circuit for about 31 hours. Now imagine that this same 10 kJ battery is used to supply power to a 555 timer circuit that drives the LED. Since the LED is blinking on and off the power consumption is not constant; the figure above (not perfectly to scale) shows how the power varies with time (note the units of milliseconds and milliwatts). Eventually, at time TF, the battery will be totally dissipated and unable to run the circuit. Solve for the time, TF, rounded to the nearest hour, that it takes for the battery to be fully depleted. You may assume a simple model in which battery runs at full voltage until the energy is depleted. Hints: remember that 1 Watt-second = 1 Joule; round to whole hours; 115 + 10.4- 135 405 540 (? t(ms) TF We saw in class today that a 9 volt battery (containing 10 kJ) could power a simple LED circuit for about 31 hours. Now imagine that this same 10 kJ battery is used to supply power to a 555 timer circuit that drives the LED. Since the LED is blinking on and off the power consumption is not constant; the figure above (not perfectly to scale) shows how the power varies with time (note the units of milliseconds and milliwatts). Eventually, at time TF, the battery will be totally dissipated and unable to run the circuit. Solve for the time, TF, rounded to the nearest hour, that it takes for the battery to be fully depleted. You may assume a simple model in which battery runs at full voltage until the energy is depleted. Hints: remember that 1 Watt-second = 1 Joule; round to whole hours