An AC adapter for a telephone-answering unit uses a transformer to reduce the line voltage of 120 V (rms) to a voltage of 9.0 V. The rms current delivered to the answering system is 400 mA. (a) If the primary (input) coil in the transformer in the adapter has 240 turns, how many turns are there on the secondary (output) coil? (b) What is the rms power delivered to the transformer? Assume an ideal transformer.
Answers: 3
Physics, 22.06.2019 03:30
As part of an industrial process, air as an ideal gas at 10 bar, 400k expands at steady state through a valve to a pressure of 4 bar. the mass flow rate of air is 0.5 kg/s. the air then passes through a heat exchanger where it is cooled to a temperature of 295k with negligible change in pressure. the valve can be modeled as a throttling process, and kinetic and potential energy effects can be neglected. (a) for a control volume enclosing the valve and heat exchanger and enough of the local surroundings that the heat transfer occurs at the ambient temperature of 295 k, determine the rate of entropy production, in kw/k. (b) if the expansion valve were replaced by an adiabatic turbine operating isentropically, what would be the entropy production? compare the results of parts (a) and (b) and discuss.
Answers: 3
Physics, 22.06.2019 04:00
Determine the maximum r-value of the polar equation r =3+3 cos 0
Answers: 3
Physics, 22.06.2019 10:00
Aria drove to the store, did some shopping, and then came home. during maria's trip, when was her displacement equal to zero?
Answers: 1
An AC adapter for a telephone-answering unit uses a transformer to reduce the line voltage of 120 V...
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