1. The Coulomb force between two charges q1 and q2 at separation r in air is F. If half of the separation is filled with medium of dielectric constant 9, what will be the value of new coulomb force? 2.There are two large parallel metallic platesP1 and P2 carrying surface charge densities σ1 and σ2(σ1> σ2) respectively, placed at some distance d apart in vacuum. Determine the work done by the electric field in moving a point charge q from P1 to P2 along a line a (a

4r-134a enters the condenser of a residential heat pump at 800 kpa and 50°c at a rate of 0.022 kg/s and leaves at 750 kpa subcooled by 3°c. the refrigerant enters the compressor at 200 kpa superheated by 4°c determine (a) the isentropic efficiency of the compressor, (b) the rate of heat supplied to the heated room, and (c) the cop of the heat pump. also, determine (d) the cop and rate of heat supplied to the heated room if this heat pump operated on the ideal vapor-compression cycle between the pressure limits of 200 and 800 kpa. (0.757, 4.37 kw, 5.12, 6.18, 3.91 kw)