HO-ED-EM-03A e/m Experiment Apparatus (Thomson’s method)

e/m Experiment Apparatus (Thomson’s method) Holmarc's e/m apparatus (Model No: HO-ED-EM-03A) is designed for the measurement of the charge to mass ratio e/m, of the electron. This equipment also facilitates the demonstration of effects of magnetic fields on a moving charged particle. It consists of a fine beam electron tube known as e/m tube, a pair of Helmholtz coils and the electronic control box. The e/m tube generates the fine electron beam by applying the accelerating voltage. The electron tube is placed between a pair of Helmholtz coils. If we apply current to the Helmholtz coil uniform magnetic field is generated and as a result the fine electron beam changes its path to circular. By measuring the accelerating potential, the Current through the Helmholtz coils and the radius of the circular electron beam, we can find out the e/m ratio. The electronic control unit provides the energy requirements for the tube and Helmholtz coil. The Helmholtz coil is a pair of coils separated by a distance of the coil radius. The e/m tube generates a fine electron beam by applying accelerating voltage. Electron collisions with the gas molecules excite the gas molecules and produce light emission in a cylindrical sheath around the electron beam. As the excited molecules relax, the electron paths become visible. Experiment: To measure the Charge to Mass ratio of Electron (e/m) The e/m ratio can be calculated using the equation, e/m   =   2.U / (r.B) * (r.B) Where B   =   K.IH K   =   (4/5)3/2. 4Л X 10-7. N/R Where V   -   Velocity e   -   Elementary Charge R   -   The radius of the Helmholtz coils N   -   The number of turns on each Helmholtz Coil I   -   The current through the Helmholtz coils B   -   Magnetic field U   -   Accelerating voltage Specifications:  Helmholtz coil pair     Coil diameter     270 mm     Winding count     150 turns per coil     Coil current     0 - 3 A     Anode voltage     0 - 300 V     Wehnelt voltage     0 to -50V     Heating voltage     5 - 7 V DC     Display     3 digit LED display     Tube’s rotatory angle     10 - 360°     Supply voltage     220 ±10 V, 50 Hz     Weight     Approx. 10 Kg     Fine beam tube T     Gas filling     Argon / Neon     Gas pressure     0.13 hPa     Measurement mark spacing     20 mm     Bulb diameter     165 mm Features:   Excellent for accurate measurements of charge-to-mass ratio     Clear observation of circular electron beam path     Change in direction of the coil current possible Graph: Video: Click HERE for Video Related Topics:   e/m Ratio     Helmholtz coil     Lorentz force     Cathode     Anode