# IB 33: Magnetic Fields

Extracts from this document...

Introduction

IB 33: Magnetic Fields

By: Nicholas Sudharta

Physics 11

Ibu Sheila

Data Collection______________________________________________________________

Distance (cm) | Averaged Field Strength (gauss) | Uncertainty (±) |

8.5 | 3.1739 | 0.06660074 |

8 | 3.2580 | 0.08718747 |

7.5 | 3.3195 | 0.10186693 |

7 | 3.4419 | 0.095267 |

6.5 | 3.5664 | 0.07096629 |

6 | 3.6786 | 0.07702821 |

5.5 | 3.8244 | 0.04278036 |

5 | 3.8688 | 0.02282731 |

4.5 | 3.8770 | 0.00607607 |

4 | 3.8800 | 0.00220119 |

3.5 | 4.0379 | 0.05665183 |

3 | 4.8100 | 0.03027302 |

2.5 | 4.8521 | 0.00298729 |

2 | 5.8212 | 0.00120247 |

1.5 | 7.6604 | 0.0510291 |

1 | 9.7198 | 0.00806366 |

0.5 | 14.5649 | 0.00089853 |

0.1 | 27.6778 | 0.0766445 |

Data Processing______________________________________________________________

Average field strength: B= Field strength at a distance

We find the average field strength by using average function in Microsoft Excel.

To find the uncertainty, we use standard deviation or STDEV in Microsoft Excel to the data range in each trial.

Standard Deviation Formula:

To graph:

Graph (including uncertainties):

From the graph, my hypothesis is that Field Strength is inversely proportional to Distance.

Middle

As from the graph shows,

To find the order or from the model formula we log the equation.

As so:

Next, from that logged model formula we use linear regression to find the value of .

Firstly, take the existing data and log the values in Microsoft Excel.

New logged data:

Distance (cm) | Averaged Field Strength (gauss) |

0.92941893 | 0.50159727 |

0.90308999 | 0.51295763 |

0.87506126 | 0.52107422 |

0.84509804 | 0.53679439 |

0.81291336 | 0.55222661 |

0.77815125 | 0.56568366 |

0.74036269 | 0.58256894 |

0.69897 | 0.5875737 |

0.65321251 | 0.58849348 |

0.60205999 | 0.58883553 |

0.54406804 | 0.60615536 |

0.47712125 | 0.68214361 |

0.39794001 | 0.68593146 |

0.30103 | 0.76501013 |

0.17609126 | 0.8842493 |

0 | 0.98765785 |

-0.30103 | 1.163308 |

-1 | 1.44213154 |

Secondly graph the data using chart wizard (including a linear trend line)*:

*In the graph, we ignore the uncertainties as it does not affect the equation shown on the chart.

Thirdly, use Microsoft Excel’s option of “Display equation on chart” as shown on the graph above. This will result in [y = -0.5114x + 0.9482]

Remembering the logged model formula:

From the graph we get the value of. The value of

Conclusion

To evaluate that point, another limitation and missing data of our experiment is that we did not record the earth’s magnetic field at the located experiment. As by doing so, we can compare the value with the theoretical value of the earth’s magnetic field of and thus find the % error of our experiment.

An alternative experiment that is aimed to find the relationship of distance from a magnetic source and magnetic field strength is to use a long wire, and having a constant current we alter the distance of the wire and the sensor.

By applying the formula: . We find the relationship between magnetic field strength (), and distance of the sensor (). Using constant values of , and , while having a constant or controlled variable of (current).

References:

Serway and Jewett, “Physics For Scientists And Engineers 6E”.

Owen John & Haese Robert & Haese Sandra & Bruce Mark, “Mathematics for the international student”.

This student written piece of work is one of many that can be found in our International Baccalaureate Physics section.

## Found what you're looking for?

- Start learning 29% faster today
- 150,000+ documents available
- Just £6.99 a month