# Determination of equivalent resistance of two resistors when connected in parallel

## 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 together between two points then they are said to be connected in parallel.

In parallel combination,

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

The formula to calculate equivalent resistance in series is: 1/Rp = 1/R1 + 1/R2 + 1/R3

## Procedure

1. Setup the devices as shown in the circuit diagram (i).
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 R1 using formula R = V/I.
6. Similarly, calculate R2 and Rp (equivalent resistance in parallel) by following above steps.

## Observations

#### For R1 :

Mean value of R1 = (2+2+2)/3 = 2 Ω

#### For R2

Mean value of R2 = (1+1+1)/3 = 1 Ω

#### For Rp

Mean value of Rp = (⅔+⅔+⅔)/3 = ⅔ Ω = 0.67 Ω

*These observations may be different for different voltmeter, ammeter and resistors.

## Calculation

$\frac{1}{R_{p}}$ = $\frac{1}{R_{1}}$ + $\frac{1}{R_{2}}$ = $\frac{1}{2}$ + $\frac{1}{1}$ = $\frac{3}{2}$

Or, Rp = $\frac{2}{3}$ Ω

## Result

• The calculated value of equivalent resistance, Rp = ⅔ Ω = 0.67 Ω
• The experimental value of equivalent resistance, Rp = ⅔ Ω = 0.67 Ω
• The equivalent resistance Ris less than the individual resistances.

## Precautions

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 Biology Practicals

• ##### vorbelutrioperbir

Thanks so much for providing individuals with a very splendid possiblity to check tips from here. It’s always so pleasant and jam-packed with amusement for me personally and my office acquaintances to visit your web site on the least thrice in one week to find out the newest tips you will have. And lastly, we’re always contented considering the surprising concepts you serve. Some 4 tips in this article are unequivocally the most effective we’ve had.

1
2
• ##### vorbelutr ioperbir

Hello.This article was extremely remarkable, especially since I was browsing for thoughts on this topic last couple of days.

• ##### vorbelutr ioperbir

Thank you a lot for giving everyone an extraordinarily breathtaking opportunity to read in detail from this site. It is usually very terrific and also jam-packed with a good time for me personally and my office friends to visit your web site not less than 3 times a week to see the newest guides you will have. And definitely, I’m so at all times amazed concerning the dazzling inspiring ideas served by you. Some 3 points on this page are truly the finest we’ve had.

0
2