simulate this circuit – Schematic created using CircuitLab

I am doing an experiment for a lab and I am confused as to what they are asking.

They ask to measure the voltage across the battery, the voltage across a 68 Ω resistor and then the current flowing in the circuit. However when measuring both the voltages they only ask to do one step that only provides one voltage.

My question is, does the voltage across the battery change, or does it remain constant regardless of the number of resistors added in series. I am using two 1.5 volt batteries and am getting a reading of 3.093 v from my multimeter.

This is what my data is looking like, don't know if the data in column 1 is correct (FYI my multitmeter might be malfunctioning but I have to stick with these numbers). raw data

I know this sounds confusing, I am confused myself. please let me know if you can help!

  • \$\begingroup\$ Welcome to EE.SE! Please draw a schematic. There is a built in tool for it if you press edit and then on the schematic symbol. It looks like you haven’t accounted for the series resistance of the battery. Try drawing it as an ideal battery in series with a resistor. Also, the last line, are you sure the resistors are not in parallel? \$\endgroup\$ – winny Dec 18 '18 at 7:14
  • \$\begingroup\$ thank you for replying. I am pretty sure the resistors are in series. how would I calculate the series resistance of the battery/ \$\endgroup\$ – j.noley Dec 18 '18 at 7:28
  • \$\begingroup\$ Does not make sense. 220+68 ohm is more than 68+68 ohm, i.e. less current and i.e. less voltage drop over the ESR of the battery. Please draw a schematic. You can even simulate right here on the webpage from your schematic and try varios values. \$\endgroup\$ – winny Dec 18 '18 at 8:07
  • 1
    \$\begingroup\$ Why don't you ask those that tell you do to this. What you're doing is very basic electronics so it must be part of a course. So there must be someone to ask questions to and that someone is tasked to explain things to you. FYI my multitmeter might be malfunctioning Then why continue at all? How can you draw conclusions make sane measurements if you cannot trust the multimeter? Drop everything now and first make sure that the multimeter is OK, compare it to a know-good multimeter for example. Any measurement is pointless if you cannot trust your tools. \$\endgroup\$ – Bimpelrekkie Dec 18 '18 at 9:07
  • 1
    \$\begingroup\$ Generally, students have a tendency to blame the equipment if things don't pan out as expected! The first four results are credible, the last one isn't. What's the probability of the equipment, which is still functioning, suddenly giving incorrect readings? \$\endgroup\$ – Chu Dec 18 '18 at 9:27

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.