# Capacitance - explore the relationship between voltage and the amount of charge stored in an object.

Capacitance Introduction Chapter 3, “Capacitance,” contains laboratory experiments designed to explore the relationship between voltage and the amount of charge stored in an object. These experiments involve measuring electrical properties of capacitors in series, in parallel, while charging, discharging, and at varying widths between the surfaces. Hands-on experience and resulting data should provide insight into the nature of capacitance. Theory In order to charge an object, a certain amount of energy is required to transfer charge to that object. The energy per unit of charge is called voltage. Given a certain voltage, charge can be transferred to an object until the amount of energy that is required to add more charge exceeds the energy potential. A derived unit is useful for expressing the capacity of charge (in Coulombs) that can be transferred to an object per unit of voltage (in Volts). Therefore, a unit of capacitance called the Farad exists, and is defined as C = Q/V. A
capacitor comprised of two parallel surfaces will have a capacitance equal to 8.85 ρF/m, times the area of one of the plates, divided by the distance between them. When sharing the charge applied to one capacitor with a second capacitor, charge is conserved, therefore Vf * (C1 + C2) = Vi * C1. When discharging a capacitor through a resistor, V(t) = V0 * e-t/RC. When charging a capacitor through a resistor, V(t) = Vf – Vf * e-t/RC. Experiments 3.5.2: Charging a Capacitor This experiment required a 9V battery, a voltmeter, and voltage a follower that were assembled in ...