A miniature, solar-powered environmental sensor runs continuously in the dark on a backup supercapacitor. The circuit operates at a constant potential difference of 2.5 V and draws an average current of 120 μA120\text{ }\mu\text{A}120 μA.
What is the electrical energy transfer to the sensor circuit during an 18-hour18\text{-hour}18-hour period of darkness?
5.4×10−3 J5.4 \times 10^{-3}\text{ J}5.4×10−3 J
0.32 J0.32\text{ J}0.32 J
19 J19\text{ J}19 J
1.9×104 J1.9 \times 10^4\text{ J}1.9×104 J
