Electrons and ions

Electricity and Magnetism Level 5

A plasma consists of a uniform density mix of heavy ions and light electrons. If one slightly displaces all the electrons in the same direction from their equilibrium positions, they will feel a restoring force towards the ions and there will be a plasma oscillation. If the density of electrons and ions is each $10^{10}$ particles per cubic meter, what is the frequency of this oscillation in Hz?