What is thermal resistance and how is it analogous to electrical resistance?

Thermal resistance (R_th) quantifies the opposition to heat flow, analogous to electrical resistance. For conduction: R_th = L/(kA), for convection: R_th = 1/(hA), and for radiation: R_th = 1/(h_rad×A). Just as voltage drives current through electrical resistance (V = IR), temperature difference drives heat flow through thermal resistance (ΔT = Q×R_th). Series resistances add directly, while parallel resistances combine reciprocally, enabling analysis of complex thermal circuits.