Ice cream sphere filled with noble gas of low pressure. The tube's two cylindrical necks are protected by plastic sleeves and are designed to fit in Helmholtz coils 765-1207. The tube is used to show how an electron beam is deflected in a magnetic field. If the tube is in a homogeneous magnetic field with sufficient strength, the electron beam becomes circular. The tube is equipped with an internal measuring scale with fluorescent markings at distances of 4, 6, 8 and 10 cm (2r) from the cathode. The tube is well suited for determining the charge-mass ratio of the electron with great accuracy.

• Anode voltage: 1,500-5,000 V DC

Suitable voltage source 765-0820.