= Charge-to-mass ratio
{title2=$q/m$}
The <charge-to-mass ratio> is a body's <electric charge> $q$ divided by its <mass> $m$. Its <SI> unit is the <coulomb> per kilogram, $\mathrm{C\,kg^{-1}}$. In a prescribed <electric field> and <magnetic field>, nonrelativistic <acceleration> depends on $q/m$ through the <Lorentz force>. Two bodies with the same initial <position>, <velocity>, and <charge-to-mass ratio> therefore have the same trajectory in this ideal model. For an <Electron>, write $q=-e$ with $e>0$ the <elementary charge>: $q/m=-e/m$, whereas the positive number $e/m$ is the magnitude of the <charge-to-mass ratio>.
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