Science Buddies: "Ask an Expert"

Hello. My name is Antuan and I have a question about my science fair project. It is on physical sciences where I am testing the magnetic field strength of a magnet at different temperatures to see if it becomes stronger or weaker with increased or decreased temperatures.

I did the experiment and as a part of the calculations (which I took in voltages), I have to convert to millivolts then to magnetic fields strength. To convert to magnetic field strength (using the Science buddies: Measuring Magnetic Fields, as a reference), I used the equation: B = V0 - V/1.3 (B = magnetic field strength in gauss (G), V0 = voltage in millivolts when no magnets are nearby (mV), V = the voltage of the magnet at a certain temperature in millivolts (mV), and 1.3 = the sensors sensitivity in millivolts per gauss (mV/G)).

So doing all of that and converting the voltages to millivolts then to magnetic field strength in Gauss, I just wanted to see if my results were heading in the right direction because I am not sure what ranges of value results I am looking for. Should it be in the hundreds? Thousands? etc.

In converting one of the voltages (2.49 V) to magnetic field strength, using the equation V0 = 2.53V (2530 mV), V = 2.49V (2490 mV), and the sensor sensitivity, 1.3V (1300 mV), I got 2528.

Are my calculations correct or incorrect?

Hi Antuan,

I'm assuming that you're working on the project described here:

https://www.sciencebuddies.org/science- ... ds#summary

Equation 1 from the procedure section can be used to calculate magnetic field strength for the experiment described. Another (and maybe more clear) way of writing equation 1 is

B = (V0-V)/1.3

That is, the voltage difference (V0-V) should be divided by the sensor sensitivity (1.3). Using the values you provided the voltage difference (2530 mV – 2490 mV) is 40 mV. And 40 mV divided by 1.3 mV/G gives 30.8 G as the magnetic field strength.

You might want to try an online search for field strengths of various magnets. Magnetic field strength units are often listed as Teslas (1 Tesla = 10000 Gauss) so you may need to convert units for comparison.

I hope this helps. Please post again if you have more questions.

A. Norman