# Homework Help: What does the . in equations stand for?

1. Mar 22, 2008

### Energize

What does the "." in equations stand for?

I've been revising electric fields, and have come across the equation $$\Delta E_{p} = k . Q_{1} Q_{2} [ \frac{1}{r_{1}} - \frac{1}{r_{2}}]$$

I have never come accross a decimal point in an equation before, what does it mean?

Last edited: Mar 22, 2008
2. Mar 22, 2008

### rock.freak667

"." is another way of saying "multiplied by"

3. Mar 23, 2008

### Air

It is to avoid using $\times$ which can be used to represent a variable. It would cause confusion hence a dot is used to show multiplication.

4. Mar 23, 2008

### chroot

Staff Emeritus
Note, it's not a period, as in [ilatex]a . b[/ilatex], it's a midline-dot, like [ilatex]a \cdot b[/ilatex]

- Warren