# Question Video: Calculating the Charge-to-Mass Ratio of a Neutron Physics

A neutron has a charge of 0 C and a mass of 1.67 × 10⁻²⁷ kg. What is the charge-to-mass ratio of a neutron?

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### Video Transcript

A neutron has a charge of zero coulombs and a mass of 1.67 times 10 to the negative 27th kilograms. What is the charge-to-mass ratio of a neutron?

Given the charge and mass of some object, in this case a neutron, its charge-to-mass ratio is simply its charge divided by its mass. In symbols, we’d write the charge-to-mass ratio as capital 𝑄 divided by 𝑚, where capital 𝑄 is the charge and 𝑚 is the mass. The units of this quantity are whatever units we use for charge divided by whatever units we use for mass. For this particular question, the calculation is quite easy because the neutron has a charge of zero and a mass that is not zero. Therefore, when we divide charge by mass, we have zero divided by a number that isn’t zero, the result of which is just zero. Carrying over the units, this gives us a charge-to-mass ratio of zero coulombs per kilogram. A charge-to-mass ratio with a numerical value of zero is characteristic of all neutral particles with nonzero mass, like the neutron. Particles like the photon that are neutral but also have zero mass do not have a well-defined charge-to-mass ratio.