Relative Charge

Relative charge is a similar concept to relative mass. It tells you how the charges of different objects compare to each other, rather than what the charges actually are. Note that charge can be positive, negative or zero which means that relative charge can also be positive, negative or zero.

A relative charge example

For example, let’s say we have four objects which have the charges shown below:

Drawing of four particles labelled A, B, C and D. Each particle is labelled with its charge: A: +5 Coulombs, B: +20 Coulombs, C: 0 Coulombs, D: -10 Coulombs.

Notice that all of the charges are multiples of five Coulombs:

  • Object A’s charge is one times five Coulombs (1 x +5C = +5C).
  • Object B’s charge is four times five Coulombs (4 x +5C = +20C).
  • Object C’s charge is zero times five Coulombs (0 x +5C = 0C).
  • Object D’s charge is negative two times five Coulombs (-2 x +5C = -10C).

Therefore, we can give object A a relative charge of +1 and then multiply by the numbers above to give the relative charges of the other objects:

Drawing of four particles labelled A, B, C and D. Each particle is labelled with its relative charge: A: +1, B: +4, C: 0, D: -2.

This allows us to easily see how the charges of the different objects relate to each other, but doesn’t show what the actual charges are.

Note that relative charge does not have units.

Relative charge is useful in chemistry

There are many situations in chemistry when we only need to know how the charges of particles compare to each other, not what they actually are. Therefore, relative charge is a very useful concept in chemistry.


Flashcards help you memorise information quickly. Copy each question onto its own flashcard and then write the answer on the other side. Testing yourself on these regularly will enable you to learn much more quickly than just reading and making notes.


What is relative charge?


What are the units of relative charge?


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