e/m By Helical’s Method

The e/m by Helical Method apparatus from Glass Agencies is a classic physics laboratory setup used to determine the charge to mass ratio of an electron by observing its motion in a magnetic field. This method is based on the principle that when electrons move with velocity perpendicular to a uniform magnetic field, they experience a force that causes them to follow a circular or helical path. In this experiment, electrons are emitted from a heated cathode inside an evacuated glass tube and are accelerated through a known potential difference. The accelerated electrons then enter a region where a uniform magnetic field is produced using a pair of coils. Due to the combined effect of the electric field used for acceleration and the magnetic field applied perpendicular to the electron beam, the electrons trace a helical trajectory. The radius of the helix depends on the electron velocity, magnetic field strength, and the charge to mass ratio. By carefully adjusting the accelerating voltage and measuring the magnetic field generated by the coils, the radius of the electron path can be observed through a fluorescent screen or scale provided within the tube. The helical motion allows accurate evaluation of the electron parameters by applying standard electromagnetic equations. The apparatus consists of a well sealed glass tube, electron gun assembly, pair of coils for magnetic field generation, power supply connections, and a calibrated scale for observation. The construction ensures clear visibility of the electron beam and stable operating conditions for repeatable results. This experimental setup helps students understand the interaction between moving charges and magnetic fields, reinforcing key concepts of electromagnetism and charged particle dynamics. The e/m by Helical Method also supports the study of Lorentz force, circular motion, and magnetic field behavior. Regular observation and calculation improve analytical skills and strengthen the connection between theoretical formulas and experimental outcomes. The apparatus is widely used in undergraduate and postgraduate physics laboratories as it provides direct insight into electron behavior under controlled conditions. The e/m by Helical Method unit supplied by Glass Agencies serves as a dependable educational tool for demonstrating fundamental principles of modern physics while supporting accurate and systematic laboratory work.