Astudent wants you to demonstrate that an electric current will produce a magnetic field.

which set of objects could be used to demostrate this?
a) a battery, a coil of wire and a compass.
eliminate
b) a compass, some paper clips and a battery.
c) a battery, an iron nail and a long copper wire.
d) an iron nail, a permanent magnet and a battery.

Which situation will have the highest resistance? a.long wire and high temperatureb.short wire and high temperaturec.long wire and cold temperaturedshort wire and low temperature

Asheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200oc and is permitted to achieve a steady-state diffusion condition. the diffusion coefficient for nitrogen in steel at this temperature is 6 x 10- 11 m2 /s, and the diffusion flux is found to be 1.2 x 10-7 kg/m2 -s. also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 4 kg/m3 . how far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3 ? assume a linear concentration profile.

It is really hard for me right know