Objectives of the Experiment
● Observe the trajectory of the electron beam in a magnetic field.
● Determine the specific charge of an electron.

How it works
A large, helium-filled electron tube is mounted between a pair of Helmholtz coils. The tube contains an electron gun, which generates a focused beam of electrons. A measured current is applied to the Helmholtz coils so that the magnitude of the magnetic field within the electron tube can be calculated. A measured accelerating potential (V) is then applied to the electron gun. The magnetic field (B) deflects the electron beam in a circular path with a radius (r) that is measured using the illuminated mm scale. From these measured values, the charge-to-mass ratio of the electron is calculated: e/ m = 2V/B²r².

Features
● Detachable helmholtz coils for high flexibility and easy storage.
● Bright, highly focused beam.
● Eliminates parallax errors for general study of electrons in am agnetic field.
● Illuminated, mirrored scale even in a dark environment.
● Rotatable tube.

Typical Result

The electron beam is initially horizontal and is visible as a weak, bluish ray.	Increase the current passing through the coils watch until the electron beam forms a closed circle.	Slightly turn the e/m tube, along with its base, around its vertical axis, thus the electron beam forms a spiral path.

Order Information