Awire with a weight per unit length of 0.071 n/m is suspended directly above a second wire. the top wire carries a current of 72.8 a, and the bottom wire carries a current of 72.7 a. the permeability of free space is 4π × 10−7 t · m/a . find the distance of separation between the wires so that the top wire will be held in place by magnetic repulsion. answer in units of mm.

Which device uses ac current to operate?

Acoal-fired plant generates 600 mw of electric power. the plant uses 4.8 x 10^6 kg of coal each day, and the heat of combustion of coal is 3.3x 10^7 j/kg. the steam that drives the turbines is at a temperature of 300° c, and the exhaust water is at 37° c. (a) what is the overall efficiency of the plant for generating electric power? (b) how much thermal energy is exhausted each day? (c) what is the change in entropy of the universe for this heat engine? (d) using the same heat reservoirs, what is the maximum possible (carnot) efficiency for a heat engine?

Which of the following is the phase that results when the moon is on the opposite side of the earth from the sun? a. quarter moon b. crescent moon c. new moon d. full moon