# Dimensions of Larmor formula

1. Nov 21, 2008

### bdforbes

The Larmor formula is:

$$P=\frac{\mu_0 q^2 a^2}{6\pi c}$$

When I checked the units of this, I got [kg m^2 s^-1]. If it is in watts, shouldn't it be [kg m^2 s^-3]? I was pretty thorough in putting everything in SI units.

$$\mu_0$$ is N/A^2 or kg m s^-2 A^-2.
$$q^2$$ is C^2 or A^2 s^2
$$a^2$$ is m^2 s^-2
c is m s^-1

Have I made a stupid error, or is this just the wrong way of doing the dimensional analysis?

This is not homework.

2. Nov 21, 2008

I don't think the formula is right.

edit: Never mind. :P

Last edited: Nov 21, 2008
3. Nov 21, 2008

### gabbagabbahey

The units of acceleration are $m/s^2$ not $m/s$, so the units of $a^2$ are [/itex]m^2/s^4[/itex] not [/itex]m^2/s^2[/itex].

4. Nov 21, 2008

### bdforbes

Stupid error it is then, thanks :P. You'd think after 4 years of uni I might be able to get that one right...