An electron gun with its collector at a potential of 100 V fires out electrons in a spherical bulb containing hydrogen gas at low pressure (`~ 10^(-2)` mm of Hg). A magnetic field of ` 2 .83 xx 10^(-4)` curves the path of the electrons in a circular orbit of radius 12.0 cm . (The path can be viewe because the gas ions in the path focus the beam by attracting electrons and emitting light by electron capture , the method is known as the 'fine beam tube ' method ) Determine e/m from the data .

Explanation

We have `eV=(mv^(2)//2) and R=(mv//eB)` which gives `(e//m=(2v//R^(2)B^(2))`, using the given data `(e//m)=1.73xx10^(11)C kg^(-1)`.