34.6 High-temperature Superconductors

A section of superconducting wire carries a current of 100 A and requires 1.00 L of liquid nitrogen per hour to keep it below its critical temperature. For it to be economically advantageous to use a superconducting wire, the cost of cooling the wire must be less than the cost of energy lost to heat in the wire. Assume that the cost of liquid nitrogen is $0.30 per liter, and that electric energy c…

Assume two galaxies are $2.00 \times 10^{2} \textrm{ }\text{Mly}$ apart. (a) How fast are they separating due to space expansion? (b) Now suppose a third galaxy is located $2.00 \times 10^{2} \textrm{ }\text{Mly}$ along a line that is a perpendicular bisector of the line segment between the first two galaxies. How fast is this galaxy separating from either of the other two galaxies? (c) Why would the third galaxy appear to be receding from both of the initially mentioned gal…