Question

An electron is emitted with negligible speed from the negative plate of a parallel plate capacitor charged to a potential difference V. The separation between the plates is d and a magnetic field B exists in the space as shown in figure (34-E20). Show that the electron will fail to strike the upper plate if

Answer 1

The force experienced first is due to the electric field due to the capacitor

E = V/d  F = eE

a = eE/m_e [Where e→ charge of electron m_e → mass of electron]

Now, The electron will fail to strike the upper plate only when d is greater than radius of the are thus formed.