Determination of equivalent resistance of two resistors when connected in series


To determine the equivalent resistance of two resistors when connected in series.

Materials Required

  • Two resistors
  • A battery eliminator
  • Ammeter
  • Plug key
  • Connecting wires
  • A piece of sandpaper
  • Voltmeter
  • Rheostat


When two or more resistors are connected end to end to each other, then they are said to be connected in series.

In series combination,

  • Current flowing is same through each resistor.
  • The potential difference across each resistor is different.

The formula to calculate equivalent resistance in series is: Rs = R1+R2

Circuit Diagram


  1. Setup the devices as shown in the circuit diagram.
  2. Plug the key and adjust the rheostat by sliding its variable terminal till the ammeter and the voltmeter show a reading.
  3. Note the readings of voltmeter and ammeter. Take out the plug or switch off the battery eliminator for a moment.
  4. Repeat the steps 2 and 3 for the different values of current by varying the sliding terminal of rheostat.
  5. Calculate resistance using formula R = V/I.
  6. Perform these steps to calculate R1, R2 and Rs.


For R1 :

S. No.Voltmeter Reading (V)Ammeter Reading (I)Resistance (R = V/I)
1.0.02 V0.01 A2 Ω
2.0.04 V0.02 A2 Ω
3.0.08 V0.04 A2 Ω

Mean value of R1 = (2+2+2)/3 = 2 Ω

For R2

S. No.Voltmeter Reading (V)Ammeter Reading (I)Resistance (R = V/I)
1.0.01 V0.01 A1 Ω
2.0.02 V0.02 A1 Ω
3.0.04 V0.04 A1 Ω

Mean value of R2 = (1+1+1)/3 = 1 Ω

For Rs

S. No.Voltmeter Reading (V)Ammeter Reading (I)Resistance (R = V/I)
1.0.03 V0.01 A3 Ω
2.0.06 V0.02 A3 Ω
3.0.12 V0.04 A3 Ω

Mean value of Rs = (3+3+3)/3 = 3 Ω

*These observations may be different for different resistors.


  • The calculated value of equivalent resistance, Rs = R1+R2 = 3 Ω
  • The experimental value of equivalent resistance, Rs = 3 Ω
  • The equivalent resistance Ris more than the individual resistances.


  1. Thick copper wires should be used as connecting wires and using sandpaper, their insulation should be removed.
  2. The connections should be tight.
  3. Voltmeter should be connected in parallel with the resistor.
  4. To avoid unnecessary heating in the circuit, the current should be passed for a short time.

Class 10 Electricity Notes Class 10 Electricity Previous Years Questions Class 10 Electricity Important Questions

Class 10 Physics Practicals

Class 10 Chemistry Practicals

Class 10 Biology Practicals


  • Shivansh preet

    If u want to being motivated in your life,
    Watch the video:-

  • Rajnish Raj

    Love u sir

    • BrainIgniter

      Love you too Rajnish!
      Cover the gaps in your learning and enjoy your study with BrainIgniter.

  • vorbelutrioperbir

    Pretty nice post. I just stumbled upon your blog and wanted to say that I have truly enjoyed browsing your blog posts. After all I’ll be subscribing to your rss feed and I hope you write again soon!

  • vorbelutrioperbir

    I enjoy you because of all your effort on this website. Betty enjoys working on internet research and it’s easy to understand why. My partner and i notice all of the compelling tactic you produce very important tactics via the web blog and invigorate response from other individuals on that concept while our simple princess is in fact learning a lot. Have fun with the remaining portion of the new year. You are always performing a superb job.

  • zoritoler imol

    It’s really a nice and useful piece of information. I am glad that you shared this helpful information with us. Please keep us informed like this. Thanks for sharing.

  • vorbelutrioperbir

    Does your site have a contact page? I’m having problems locating it but, I’d like to shoot you an email. I’ve got some recommendations for your blog you might be interested in hearing. Either way, great website and I look forward to seeing it expand over time.


The maximum upload file size: 100 MB. You can upload: image. Drop file here