|You can 'see' magnetic fields using iron filings. You can measure magnetic fields using a magnetic field sensor connected to a computer. How, for example, does that field vary as you move through a coil? Is there a connection between the field and the distance moved through the coil?
| What you need
Clamp stand, Helmholtz coils, leads, power supply, metre rule, interface, magnetic field sensor. Also your sensing software should allow you to enter distances at the keyboard - but it's not too bad if not.
Set up the apparatus as shown. Connect the magnetic field sensor to the interface. If the sensor is adjustable, set it to a fairly sensitive range such as 0-10 mT.
Start your sensing software - it may recognise the sensor automatically but if not set up the software to do so.
The software also needs to know that you will be entering distances, of between 0 and 100 cm, using the keyboard. While you are recording, you should be prompted to enter the distance you have moved the probe. Not all sensing software can do this - so an alternative approach is given here:
- Start recording. Put the probe next to the coil and type in 0 for the distance. Move the probe 1cm into the coil. Type in 1 for the distance. Continue moving the probe and entering the distance each time.
- Start recording. Move the probe at a steady speed into the coil.
How is increasing magnetic field shown on your graph?
How does the field strength change with distance?
How important is it to enter the distance along the coil via the keyboard? Can't you just move the probe steadily?
Activities in this section adapted from The IT in Science book of Data logging and Control. © IT in Science and may be reproduced as needed for use within your school.