A safety time-delay circuit in a marine distress beacon is shown below.
The DC power source has an electromotive force (e.m.f.) E=12.0 VE = 12.0\text{ V}E=12.0 V and negligible internal resistance. The circuit contains a resistor of resistance R=82 kΩR = 82\text{ k}\OmegaR=82 kΩ connected in series with an uncharged capacitor of capacitance C=470 μFC = 470\ \mu\text{F}C=470 μF.
At time t=0t = 0t=0, the switch SSS is closed to begin charging the capacitor. The micro-controller in the beacon is programmed to trigger an emergency signal when the potential difference across the capacitor reaches 8.50 V8.50\text{ V}8.50 V.
Calculate the time delay ttt before the beacon is triggered.
