Electric Circuit and Internal Resistance Lab

[jeff876]

Homework Statement

I performed a lab where we designed an electric circuit on paper and then calculated the Current, Power, and Voltage for each of the resistors. We used one power supply. Then we built the circuit we designed and then measured the actual Current Power and Voltage for the it using a multimeter. However, all the values for the actual measurements are just slightly lower than the numbers of the predicted values. I think it has to do with the internal resistance of the battery, but i am not sure. Would i calculate it using V=IR and use the actual total voltage and total current?

Homework Equations

V=IR

The Attempt at a Solution

 

[Delphi51]

Yes, use the actual values in your calculation. A good idea to have thought of internal resistance - and to calculate it.

You might also want to mention imperfect meters. Current meters have to be inserted in the circuit and they add resistance to it. Voltmeters have less than infinite resistance and draw some extra current.

Meters can be out of whack, too. Not a bad idea to check your meter against another one in the lab or some reference voltage such as a disposable AA battery.

 

[nlightner]

Based on your description, it is likely that the difference between the predicted and actual values is due to the internal resistance of the battery. When calculating the predicted values, it is important to consider the internal resistance of the power supply, as it can affect the overall circuit performance. To calculate the internal resistance, you can use the equation V=IR, where V is the total voltage measured from the power supply, I is the total current measured from the circuit, and R is the internal resistance. Once you have calculated the internal resistance, you can subtract it from the total resistance in your circuit to get a more accurate prediction of the actual values. It is also important to note that the internal resistance of the battery may vary depending on the age and condition of the battery, so it is important to measure and account for it in your calculations. Overall, considering the internal resistance of the battery is crucial in accurately predicting and measuring the values in an electric circuit.