RC circuit lab report - Essay Example

Insert of Measurement of voltage across a capacitor A capacitor is a circuit element designed to store energy transferred across an electric system in a closed loop. When the circuit is closed, current begins to flow through the connection wires, some of which are stored by the capacitor. The amount of charge increases steadily until the maximum amount of charge designed for the capacitor to store is reached. At this point (when an optimum charge has been achieved), the capacitor ceases to charge despite the increase in the voltage of the current flowing across the loop.

Contrarily, when the circuit is opened, the connection is broken and current ceases to flow within the loop. The capacitor then begins loosing its charge and eventually becomes discharged over time. The amount of charge stored by a capacitor however is determined by the length of time for passing the current and the amount of charge being transferred across the loop. This paper will demonstrate the process of charging and discharging a capacitor using an AC, I, current over a period of time, T.

the amount of charge acquired by the capacitor, Q is measured and the capacitor allowed to freely discharge over some time. The paper will as well look at the general factors which affect the amount of charge that is stored by a capacitor over a length of time. This will be done by answering certain specific questions of inquiry commonly encountered during a laboratory research experiment. The voltage, V, across the capacitor over time during charging and discharging can be given by the following equation; Q= CV, V is therefore given by the equation V= Q/C.

However, Q (t) = Q (I) while the capacitor is charging or discharging. We can therefore use the three equations to derive the equation for obtaining the amount of voltage flowing across the circuit over a period of time, t, by combining the two equations. This voltage can then be calculated by the equation V= Qt/C whereby, t, is the amount of time taken to the charge to flow in the circuit and V, the voltage across the capacitor over the length of time, t. one doesn’t need the data point exactly at the point t= 0 for him or her to derive the constant in time across the circuit.

This is because the time constant is the gradient of the graph obtained after plotting the values of Q against t/RC. This constant (gradient of the graph can be obtained at any point without necessarily projecting the graph to point 0) hence the constant of time during charging and discharging processes. However, the experiment has a lot of flaws hindering the acquisition of accurate measurements of both the voltage stored in the capacitors during charging and that lost during the discharge processes as well as the capacitance of the resistors.

These flaws often act as the sources of errors in such experiments. The flow of current within the circuit is often affected by several factors varying from the material composition of the wires used in connection and the length of the same. To begin with, the length of the wires used in connection can affect the flow of current through the connection circuit by increasing the distance over which current flows. These often increases the resistance to the flow of current due to the realignment of the dipoles to enable current flow.

The length L of the connection wire is therefore a great source of errors in the flow of current (Bird). Moreover, the transmission of the current across the loop is as well is abject to external environmental interferences such as the changes in temperature t over time as the current is transmitted across the loop. This is because of the occurrence in the internal resistance of the wires which keeps on increasing over time as the current flows. The increase in temperature often lowers the flow of current within the loop, hence a reduction in the amount of voltage stored by the capacitor per unit time and increases the resistance per unit time.

Resistors used in almost every electrical device used everywhere in the world such as radios, televisions, telephones, cars among other devices that utilizes electricity in their connectivity. As has been mentioned, the resistors acquire and store charges as current flows through them over time (Bird). Depending on the recommended voltage storage for the resistor and the amount of work needed to be done by the stored charges (sometimes determined by the size of the device), the voltage stored by each varies a great deal.

The need to disconnect and discharge the battery negative before carrying out any repair operation on the car is meant to discharge the capacitors to prevent accidents during the operations through electric shocks. The repairer is required to wait for sometime for the capacitor to fully discharge in order to ensure that all charges have been lost. The process of voltage loss from a capacitor takes a bit of time depending on the amount of charge that was injected into the capacitor hence the need to wait for some time, about two minutes to ensure that the stored charges are all lost.

If another device with a smaller resistance such as a screwdriver is introduced and made to touch both leads of the capacitor, the discharge time will be lowered and the capacitor will discharge at a higher rate than normal. This is because the device with a smaller resistance facilitates the outflow of charges further speeding the discharge process. In conclusion, I would like to mention here that the capacitors are very crucial in electric connections of various devices across the globe. The choice of a capacitor is however influenced by the amount of charges required to be stored for the right kind of work to be done.

The amount of charge, measured in voltage, stored by a capacitor is influenced by the resistance of the wire, the amount of current flowing within the closed loop and the time of exposure or transfer of the current through the wire as well as the external factors influencing the cooling and heating of the transmission wires further influencing the resistivity of these wires. Work Cited Bird, John,. Electrical and Electronic Principles and Technology. London: Routledge, 2010.