Physics Impact Factors
Impact factors are calculated based mostly on number of citations. There are, however, many other factors. Do a google search on "ISI Journal Impact Factors" or "Journal Performance Indicators" and you can pull up some formulas that the ISI uses.
Regarding the actual impact factors, it depends on the area of physics. Areas available are:
Applied
Atomic, Molecular & Chemical
Condensed Matter
Fluids & Plasmas
Mathematical
Multidisciplenary
Nuclear
Particles & Fields
Here is some info. for 2002:
Top five ranked impact factor "Applied Physics" journals:
Mat Sci Eng R - 11.893
Adv Func Mater - 4.656
Appl Phys Lett - 4.207
MRS Bull - 3.242
J Appl Phys - 2.281
And the top six ranked impact factor "Atomic..." journals:
Prog Nucl Mag Res SP - 4.808
Adv Atom Mol Opt Phy - 4.524
Chem Phys Chem - 3.862
Atom Data Nucl Data - 3.737
J Chem Phys - 2.998
Phys Rev A - 2.986
Top five "Condensed Matter ..." journals:
Adv Phys - 13.952
Solid State Phys - 6.600
Adv Funct Mater - 4.656
Prog Surf Sci - 4.096
Phys Rev B - 3.327