Transverse ac susceptibility of strips and disks with complex linear resistivity

The linear ac susceptibility in a transverse magnetic ac field is calculated for thin strips and disks with arbitrary complex resistivity ρac({ω}). The exact result is approximated with high precision by a finite sum. This analytic expression allows one to extract ρac({ω}) from contact-free magnetic measurements on high-Tc superconductors in search for scaling laws and phase transitions. As an example the susceptibility of a superconducting disk with pinning and thermally assisted flux flow is given.