The wall of a building measures 8 m horizontally by 3 m vertically, and consists of 250- mm-thick concrete. on the inside it is covered with 140-mm-thick extruded polystyrene insulation. the wall has a 1.4 m × 1.0 m door of 12-mm-thick plywood with no insulation. outside and inside air temperatures are -5°c and 18°c, respectively. the corresponding convection heat transfer coefficients are 38 w m2 k-1 and 7 m-2k-1. calculate the rate of 1151 (a) heat transfer through the wall

To understand the behavior of the electric field at the surface of a conductor, and its relationship to surface charge on the conductor. a conductor is placed in an external electrostatic field. the external field is uniform before the conductor is placed within it. the conductor is completely isolated from any source of current or charge. part a: which of the following describes the electric field inside this conductor? it is in the same direction as the original external field.it is in the opposite direction from that of the original external field.it has a direction determined entirely by the charge on its surface.it is always zero. part b: the charge density inside the conductor is: 0non-zero; but uniformnon-zero; non-uniforminfinite part c: assume that at some point just outside the surface of the conductor, the electric field has magnitude e and is directed toward the surface of the conductor. what is the charge density η on the surface of the conductor at that point? express your answer in terms of e and ϵ0