Discharge of a Capacitor

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INVESTIGATING THE DISCHARGE OF A CAPACITOR AIM The aim of the experiment is to examine the theoretical nature of a capacitor and to investigate how the capacitor discharges by doing an experiment in relation between the potential difference, resistance and capacitance. INTRODUCTION A capacitor is defined as an electrical device that can store energy in the electric field between a pair of closely spaces conductor known as plates (Ask Jeeves, Capacitors). In a way, the capacitor is like a battery as they store electrical energy, however, unlike the battery, capacitors are unable to produce new electrons, but can only store them (How Stuff Works, Capacitors). When a capacitor is connected to a battery, the plate that is attached to the negative terminal of the battery accepts the electrons being produced, whereas the plate that is attached to the positive terminal of the battery loses electrons to the battery. Once it’s charged, the capacitor will have had the exact same voltage as the battery (How Stuff Works, Capacitors). Capacitance is termed as the ability of a system to store an electric charge (Q) on conductors to the potential difference (V) between them. The SI unit of capacitance is known as Farad (F), which is equal to one Coulomb pet volt (1C/V). Once the capacitor is disconnected from the battery, the capacitor immediately begins to discharge once it has been connected to a resistor and a closed circuit until the capacitor has run out of charge inside it. Using the equation below, we will find out how the potential difference of the capacitor decreases with time: CVT = CV0e-t/RC VT = V0e-t/RC The fact that RC = time constant, proving the time it takes for the charge to decay to 1/e of the initial value, can be shown below: QT = Q0e-t/RC Q0/2 = Q0e-t/RC 12 = e-t/RC ln12 = -tRC ln2 = tRC T1/2 = ln2RC METHOD V + - 3V Battery pack

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