# What is charge to mass ratio of proton and alpha particles?

By BYJU'S Exam Prep

Updated on: September 25th, 2023

The charge-to-mass ratio of proton and alpha particles is 2: 1 as the charge-to-mass ratio of a proton particle is double that of an alpha particle. The charge-to-mass ratio (Q/m), as the name implies, is calculated by dividing an object’s charge by its mass. Only things that fit the definition of a particle can frequently benefit from this quantity. The alpha particle is made up of two protons and two neutrons.

### Alpha particle to proton charge mass ratio

Step 1: We will first determine the charge mass ratio of the proton and alpha particle:

Let’s consider.

We know that The proton’s charge is +e

And m = proton mass

The proton has a particular charge of e/m.

e = 1.6 x 10-19 C and m = 1.67 x 10-27 kg

Thus specific charge mass ratio of proton = 9.67 x 107 Ckg-1

• The charge of helium is +2e.
• The mass of helium is 4m.
• The specific charge of helium is 2e/4m.

Specific charge of an alpha particle = 2 x 1.67 x 10-27 C/4 x 1.66 x 10-27 kg

Thus the specific charge of alpha particle = 4.82 x 107 C/kg.

Step 2: now we have to find the ratio of these two(alpha particle and proton):

Thus the ratio = (e/m)/(4m/2e) = 9.67 x 107 C/kg-1/ 4.82 x 107 C/kg.

As a result, the charge-to-mass ratio of a proton particle is 2:1, which is twice that of an alpha particle.

Summary:

## What is charge to mass ratio of proton and alpha particles?

The charge-to-mass ratio of a proton is two times greater than that of an alpha particle, hence the ratio between their masses is 2:1. The discovery of protons dates back to the year 1815 when the English chemist William Prout suggested that all atoms are made up of hydrogen atoms.

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