Two infinitely long coaxial cylindrical surfaces, r=a and r=b (b> a), carry surface charge densities ps and peb, respectively carry surface charge densities (a) determine e everywhere. (b) what must be the relation between a and b in order that e vanishes for r> b?

Acarpenter builds an exterior house wall with a layer of wood 2.9 cm thick on the outside and a layer of styrofoam insulation 2.3 cm thick on the inside wall surface. the wood has k=0.080w/(m⋅k), and the styrofoam has k= 0.010 w/(m⋅k). the interior surface temperature is 19.0 ∘c , and the exterior surface temperature is -15.0 ∘c . a.)what is the temperature at the plane where the wood meets the styrofoam? celsius b.)what is the rate of heat flow per square meter through this wall? /m^2