# Fermi's constant

1. Mar 9, 2008

### randa177

what is the value of fermi's constant ( GF ) in SI units?
I tried to work it out, but it seems that I'm wrong, I got a value of: 6.5 X 10(41) J(-2)

Does it make sense?

2. Mar 9, 2008

### Norman

$$G_F = 4.54376275 \times 10^{14} J^{-2}$$

where

$$\frac{G_F}{(\hbar c)^3} = 1.16637 \times 10^{-5} GeV^{-2}$$

I used the following code in Google:

Code (Text):

1.16637*10^-5 (GeV)^-2 in (Joules)^-2

3. Mar 9, 2008

### randa177

so, you mean Gf / (h.bar X c) ^ 3 = 4.5 X 10 (14),,, [ not the Gf itself] right?

4. Mar 9, 2008

### randa177

how to get it in cgs units,,, I don't know how to use google to convert the units!

5. Mar 9, 2008

### pam

If you know it in Joules, just convert Joules to ergs.