• Study of the motion of charged particles in a magnetic field;
• Experimental determination of the specific charge of an electron.

The main element of the setup is a vacuum tube placed in a region of uniform magnetic field. An electron gun is installed inside the tube. The electron beam it forms causes the residual gas to glow, which makes the electron trajectory visible. The power supply allows changing both the voltage on the electron gun electrodes and the induction of the magnetic field created by the Helmholtz coils. The induction of the magnetic field and the voltage on the electron gun electrodes are measured by sensors, and the electron beam trajectory is recorded using a video recorder.

To determine the specific charge of an electron, the experimental points are plotted on a graph plotted in coordinates (B2/2U, 1/R2). The radius of the electron trajectory is determined taking into account the scale of the photograph by superimposing a circle on the image of the trajectory. In the coordinates chosen in this way, the dependence is linear with an angular coefficient numerically equal to the specific charge of an electron. To obtain the average value of the specific charge of an electron, a straight line is drawn on the graph using the least squares method, which best approximates the experimental points.