(Solved): A 100F capacitor is used in a mains-powered digital clock to provide a shortterm power backup to ...

A $100?\mathrm{F}$ capacitor is used in a mains-powered digital clock to provide a shortterm power backup to a time-keeping circuitry in the event of a power failure. Whilst the mains power is available, the capacitor is charged to $10\mathrm{V}$. The timekeeping circuit presents $1\mathrm{M}?$ resistance to the power supply and it is unable to function when the supply voltage falls below $3.5\mathrm{V}$. 1. Draw a circuit diagram for the power-failure scenario, including the capacitor and the load resistance. 2. From full-charge, how long will this capacitor keep the time circuit working?