To measure the specific charge(e/m) of an electron by using J. J. Thomson’s Method.
- Observation table for diameter of the rings Vs accelerating voltage
Helmholtz coils of radii = 14 cm.
Number of turns = 160 on each coil (n)
Permeability of free space = 4π ×10-7N/A2
e/m = 1.77 x 10 11 coul/kg.
Draw the Diameter2 Vs accelerating voltage graph and calculate e/m from the slope using equation (7).