“PHET" simulator was an excellent remote-teaching tool during the “COVID-19" pandemic times. In this article, we use this simulator to demonstrate the charging and discharging processes of a capacitor via a DC circuit. A simple circuit consists of a battery, a resistor and a capacitor is exploited to explain the charging process by converting the battery's voltage into a stored electric energy inside the capacitor. After the full charging of the capacitor, the battery is removed and the stored energy is allowed to discharge through a resistive load. During both processes of charging and discharging, it is available to record the voltage across the capacitor and/or across the resistor as functions of time. Then, these values are used to obtain other related, to the capacitor, quantities. This work is appointed to the students at the early university levels in the faculties of science and engineering who have some difficulties to understand the basics of this experiment. Almost, the difficulties are due to the brief derivations of the principal equations in the physics textbooks. Therefore, detailed derivations of the whole relevant mathematical relations are presented, in this article, and are correlated to the generated results in this work. The evaluation of the simulated experiment and the detailed mathematical derivations as well as analyzing the obtained data would serve the deep understanding of the targeted experiment's aims.