A microscopic dust grain in an industrial electrostatic precipitator has a net positive charge of 1.6×10−14 C1.6 \times 10^{-14}\text{ C}1.6×10−14 C and is located at a point where the electric potential is +2.5 kV+2.5\text{ kV}+2.5 kV.
What is the electrical potential energy of the dust grain at this point?
6.4×10−18 J6.4 \times 10^{-18}\text{ J}6.4×10−18 J
6.4×10−18 J C−16.4 \times 10^{-18}\text{ J C}^{-1}6.4×10−18 J C−1
4.0×10−11 J4.0 \times 10^{-11}\text{ J}4.0×10−11 J
4.0×10−11 J C−14.0 \times 10^{-11}\text{ J C}^{-1}4.0×10−11 J C−1