for various materials. Steel has the ability to absorb more heat as temperature
increases. This means that more energy is required to heat steel when it
is hot than when it is cold. Table 2.1 shows the difference in resistivity at
room temperature between copper and steel with steel showing about ten
times higher resistance than copper. At 760 °C (1400 °F) steel exhibits an
increase in resistivity of about ten times larger than when at room temperature.
Finally, the magnetic permeability of steel is high at room temperature,
but at the Curie temperature, just above 760 °C (1400 °F), steels become
nonmagnetic with the effect that the permeability becomes the same as air.