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Find the relationship between the current through a resistor and the voltage across it.

Extracts from this document...

Introduction

Gunjan Jain

11D

May 8, 2007

MYP Physics Practical – Current and Voltage

Aim:

To find the relationship between the current through a resistor and the voltage across it.

Apparatus:

Power pack, Leads, Ammeter, Voltmeter, Resistor (Nichrome Wire)

Method:

Assemble the circuit shown above. Vary the emf of the power pack from 0 to 12 Volts. Measure the current on the ammeter and voltage on the voltmeter for each value of emf.

Data Collection:

Thin Nichrome Wire

EMF

Current (Amperes)

Voltage (Volts)

0

0

0

2

0.15

1.75

3

0.27

2.5

4

0.38

3.25

5

0.5

4.25

6

0.6

5

8

0.85

7

10

1

9

12

1.2

10.5

Medium Nichrome Wire

EMF

Current (Amperes)

Voltage (Volts)

0

0

0

2

0.38

1.6

3

0.5

2.4

4

0.8

3.2

5

1

4

6

1.2

5

8

1.6

6.5

10

2

8.5

12

2.35

10

...read more.

Middle

-

-

12

-

-

Data Processing:image00.png

image01.png

image02.png

Conclusion:

        From the three graphs above it can be seen in all of them that there is a firm relationship between the two factors, one being voltage and second one being current. Therefore I have accomplished my aim, as I have found what is the relationship between the current through a resistor and the voltage across it. The relationship as can be seen from the graph is positive, and thus directly proportional. This can be seen from the graph itself, because firstly, the best-fit line is a straight line going through all the points, in a positive direction. Secondly, it is proportional because the graph is going through the origin.

        If we carefully look at the graph, and the results we can see that if the voltage divides the current in each specific wire, the number comes the same. In 1826, George Ohm had conducted several experiments with different metal wires to discover how the current through each depended on the voltage applied across its ends.

...read more.

Conclusion

(for error 5) before starting the experiment, it could be kept in mind to keep the wire the same length by measuring it.

Above I have written the ways to improve some of the errors. Error 2 cannot be improved, upon because the school doesn’t have a voltmeter/ammeter which could go above a specific range and thus it didn’t give us specific results for the thick wire we wanted. Error 3 cannot be improved upon because keeping the temperature constant with so many people in the room is not possible. Error 4 cannot be improved upon as there always has to be some human error. No human is 100% perfect, and thus not all errors can be removed. But they can be improved upon, and reduced to a certain limit.

To further extend this experiment, we could do the following:

  • Use a variety of thickness of wires.
  • Using other materials other than a Nichrome Wire in order to test resistance.
  • Testing other variables like the effect of temperature on resistance.
  • By improving upon the errors.

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...read more.

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