Determination of equivalent resistance of two resistors when connected in series
Aim
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
Theory
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

Procedure
- Setup the devices as shown in the circuit diagram.
- Plug the key and adjust the rheostat by sliding its variable terminal till the ammeter and the voltmeter show a reading.
- Note the readings of voltmeter and ammeter. Take out the plug or switch off the battery eliminator for a moment.
- Repeat the steps 2 and 3 for the different values of current by varying the sliding terminal of rheostat.
- Calculate resistance using formula R = V/I.
- Perform these steps to calculate R1, R2 and Rs.
Observations
For R1 :
S. No. | Voltmeter Reading (V) | Ammeter Reading (I) | Resistance (R = V/I) |
1. | 0.02 V | 0.01 A | 2 Ω |
2. | 0.04 V | 0.02 A | 2 Ω |
3. | 0.08 V | 0.04 A | 2 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 V | 0.01 A | 1 Ω |
2. | 0.02 V | 0.02 A | 1 Ω |
3. | 0.04 V | 0.04 A | 1 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 V | 0.01 A | 3 Ω |
2. | 0.06 V | 0.02 A | 3 Ω |
3. | 0.12 V | 0.04 A | 3 Ω |
Mean value of Rs = (3+3+3)/3 = 3 Ω
*These observations may be different for different resistors.
Result
- The calculated value of equivalent resistance, Rs = R1+R2 = 3 Ω
- The experimental value of equivalent resistance, Rs = 3 Ω
- The equivalent resistance Rs is more than the individual resistances.
Precautions
- Thick copper wires should be used as connecting wires and using sandpaper, their insulation should be removed.
- The connections should be tight.
- Voltmeter should be connected in parallel with the resistor.
- 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
- To study the dependence of current on the potential difference with graph
- Determination of equivalent resistance of two resistors when connected in series
- Determination of equivalent resistance of two resistors when connected in parallel
- Determination of the focal length of Concave mirror by obtaining the image of a distant object
- Determination of the focal length of Convex lens by obtaining the image of a distant object
- Tracing the path of a ray of light passing through a rectangular glass slab for different angles of incidence
- Tracing the path of the rays of light through a glass prism
Class 10 Chemistry Practicals
- Finding the pH of the samples by using pH paper/universal indicator
- Studying the properties of acids and bases (HCl & NaOH) on the basis of their reaction
- Performing and observing the reactions and classifying them into: i. Combination reaction, ii. Decomposition reaction, iii. Displacement reaction and iv. Double displacement reaction
- Observing the action of Zn, Fe, Cu and Al metals on the salt solutions
- Studying the properties of acetic acid (ethanoic acid)
- Studying saponification reaction for preparation of soap
- Studying the comparative cleaning capacity of a sample of soap in soft and hard water
Class 10 Biology Practicals
- Preparing a temporary mount of a leaf peel to show stomata
- Showing experimentally that light is necessary for photosynthesis
- Experimentally show that carbon dioxide is given out during respiration
- Studying (a) binary fission in Amoeba, and (b) budding in yeast with the help of prepared slides
- Studying homology and analogy with the help of models/charts of animals and models/charts/specimens of plants
- Identification of the different parts of an embryo of a dicot seed (Pea, gram or red kidney bean)
Comments
Shivansh preet
If u want to being motivated in your life,
Watch the video:- https://youtube.com/shorts/WDIs9FBnoB0?feature=share
Rajnish Raj
Love u sir
BrainIgniter
Love you too Rajnish!
Cover the gaps in your learning and enjoy your study with BrainIgniter.