Tubes and 500V power supplies are borrowed from the first floor labs.

In 2026 I modified the magnetic deflection coil, moving it to the outside of the plastic shield and sliding it forward. This created a more uniform field over the drift region which resulted in better agreement with accepted value for e/m and eliminated the need to guestimate the effective drift region due to falloff of the field near the front of the tube.

I have the PHYS142 students use the magnetometer in the IoLab device to determine the current to field factor and test for uniformity. No IoLab accessories are needed, just the device and dongle.

I typically use the dual 50V power supplies from electronics as they have fine control over the current to the magnetic field coils without popping a circuit breaker.

I do have students wire up the tubes. To protect the tube filament I inserted a small cork into the 12Vac input on the 500V power supplies.