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Experimental Verification of Ohm's Law

Extracts from this document...

Introduction

Experimental Verification of Ohm’s Law

Apparatus

  • E.M.F Source – Battery of 2 X 1.5V Cells
  • Battery Holder
  • Switch
  • Variable Resistor (Rheostat)
  • Ammeter (preferably digital)
  • Voltmeter (preferably digital)
  • Sample of conductor to be tested (Nichrome wire) – 10cm
  • Connecting Wires
  • Crocodile Clips

Procedure:

  • Choose the ranges of the ammeter and the voltmeter to suit the particular conductor to be tested. (e.g. 0-2V and 0-1A)
  • Set up the circuit as shown above.
  • Make sure that the voltmeter is connected in parallel across and the ammeter is connected in series with the conductor.
  • Ammeters and Voltmeters have terminals marked + and – which must be connected correctly to the battery. Only close the switch when you are sure that you have wired the circuit properly.
  • Close the switch and smoothly adjust the rheostat from minimum resistance to maximum resistance and at regular intervals note the meter reading and hence obtain a set of values from the two meters (at least 6).
  • Divide the Voltage by the current to get Resistance and tabulate the results in a table as shown below
...read more.

Middle

Current Reading 3

Voltage Reading 3

Current/ Voltage

Current Reading 4

Voltage Reading 4

Current/ Voltage

Current Reading 5

Voltage Reading 5

Current/ Voltage

Current Reading 6

Voltage Reading 6

Current/ Voltage

Graph the results using a suitable scale. Have Voltage on the X-Axis and the Current on the Y-Axis and draw a line of best fit as shown below.  You can calculate the resistance using the gradient of the line which should pass through the origin showing the relationship that Voltage is directly proportional to Current and the constant of proportionality is the resistance of the conductor.

image00.png

Results Obtained

...read more.

Conclusion

To reduce the sources of error, a umber of measures can be taken. Firstly, the switch should not be closed until you are absolutely ready to start the experiment and take the readings straight away. Also, the temperature of the wire should be checked before the experiment to ensure that it is at normal temperature.

Also, we could immerse the nichrome wire in a beaker of water to ensure that its temperature remains constant throughout the experiment and does not increase with an increase in resistance. We could also disconnect the wire from the circuit after taking every reading and allow it to cool down before taking the next reading.

Also, we could repeat the experiment for accuracy and we could also use other conductors of slightly less resistivity such as copper to prevent the temperature from increasing so quickly.

...read more.

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Here's what a teacher thought of this essay

3 star(s)

This is a brief report that has an appropriate structure but is incomplete.
1. The report is missing several sections, such as an aim, hypothesis and variables section.
2. The conclusion should quote data to back up the patterns.
3. The evaluation is missing a subheading and should suggest further research opportunities.
***

Marked by teacher Luke Smithen 13/08/2013

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