A coil of a moving-coil loudspeaker has a mean diameter of 40mm and is wound with 1011 turns. It is situated in a radial magnetic field of 0.3 T. Calculate the force on the coil in newtons, when the current is 15 mA

Athin walled concentric tube exchanger is used to cool engine oil from 160°c to 60°c with water that is available at 25°c acting as a coolant. the oil and water flow rates are each at 2 kg/s, and the diameter of the inner tube is 0.5 m and the corresponding value of the overall heat transfer coefficient is 250 w/m2. oc. how long must the heat exchanger be to accomplish the desired cooling? cpwater=4.187 kj/kg-candcpengine el=2.035 kj/kg·°c, oil . 120]