e/m Tube, ELWE

This vacuum tube is used to determine the ratio of the electron's charge to its mass (e/m). The electron beam is visible on the fluorescent screen and is deflected in the magnetic field of Helmholtz coils, while a built-in measuring scale is used to read off the diameter of the circular path. The tube is mounted on a base with safety sockets for clear, straightforward connection. In e/m experiments pupils quantify the relationship between orbital radius, magnetic field strength and accelerating voltage to derive e/m, and the exercise can be extended with uncertainty analysis and linearisation. Recommended power supply: 500 V DC (365580).