1. The problem statement, all variables and given/known data In an electric circuit, consisting of copper wires with cross section area of Sc=5mm2 and a temperature of t=25C, a lead fuse is added melting when the copper wire temperature increases by Δt=25C. Find the cross section area of the lead fuse wire Sl=x. specific heat: cc=400J/kg*C cl=140J/kg*C. Lead melting point tl=327C, latent heat λ=25000J/kg. Specific electrical resistances of the materials: ρc=0,017*10-6Ωm, ρl=0,21*10-6Ωm. material density: ρc1=8,9*103kg/m3, ρl1=11,34*103kg/m3. 2. Relevant equations Q=cmΔt Q=λm R=lρ/S Thank you for any ideas on how to solve this, if there is something confusing please ask, this equation is translated from a different language so there may be inaccuracies and such.