# e/m of electron

## Notes

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Equipment: digital multi-meter used to monitor current to the e/m device HP62168 power supply unknown make (Model 813) high voltage supply and The electron diffraction device. (EDD) Digital micrometer for measuring ring size

Using two power supplies. The HP 62168 is being used to supply the heater across the C connectors on the diffraction device. The HV supply + side is connected to the multi-meter for current reading. The HV positive supply is connected via the multi-meter to connector G7 on the EDD. The negative side is connected to C5

I found the lab manual a bit wanting in precise directions for the setup, thanks to Chad for his help. The following drawing is the way I set up the diffraction device for my experiment.

Once set up I set the high voltage to 5, 4.5, 4, 3.5 and 3 KV. I took data in this sequence measuring 10 times both the small and the large rings.

The rings are not very clear, especially this is so as the voltage is broght down and the rings expand. I measure from the outside of the right edge to the inside of the left edge of the ring on one measurement, then reverse this on the next. I also change my axis, so I am not always measuring across the horizontal; sometimes vertical or anywhere in between. I am intentionally altering the measurement point to avoid any spot that has distortion.

Inner and outer ring diameters are in mm.

5 KV

Inner: 24.59 25.10 22.45 24.97 22.90 23.48 23.88 22.15 22.75

Outer: 38.9 38.45 38.27 38.65 38.22 38.43 38.44 38.35 38.10 38.17

4.5 KV

Inner: 25.37 24.49 23.98 24.22 24.06 24.68 24.42 24.15 24.13 24.51

Outer: 41.88 41.33 42.15 40.19 41.13 40.42 40.33 40.25 40.94 40.63

4.0 KV

Inner: 25.58 25.36 26.69 25.20 25.36 25.26 24.92 25.78 25.69 24.88

Outer: 42.92 42.86 43.40 42.45 42.98 43.26 42.51 42.88 42.79 42.60

3.5 KV

Inner: 28.72 29.03 29.21 27.18 26.57 27.52 26.60 25.94 26.28 26.62

Outer: 48.32 46.65 49.77 48.90 47.20 48.42 44.84 46.28 45.47 45.20

3.0 KV

Inner: 32.49 34.82 33.65 32.83 35.45 31.54 32.56 33.40 32.86 32.70

Outer: 54.01 54.02 53.45 54.71 54.25 53.74 54.01 53.87 53.93 54.65

## Temp

According to this article the Earths magnetic field at the surface of the Earth ranges between 30 and 60 micro tesla (0.3-0.6 gauss)[| wikipedia: earth's magnetic field]

B = ((7.8 × 10−4) * I ) weber/m^2: weber/m^2 = tesla