An electron is near a proton exhibiting a non-uniform electric field. The electron moves to a distance of 2.5 nm from the proton. What is the electrical potential energy of the electron in this point charge? (-9.21 x 10-20 J) (have answer, need work)

You have a resistor and a capacitor of unknown values. first, you charge the capacitor and discharge it through the resistor. by monitoring the capacitor voltage on an oscilloscope, you see that the voltage decays to half its initial value in 3.00 ms . you then use the resistor and capacitor to make a low-pass filter. what is the crossover frequency fc?