If you removed the core from an electromagnet, which of the following would occur?

A.)The magnetic field would be greatly weakened.
B.)The electric current in the coils would be greatly reduced.
C.)The poles of the magnetic field would be reversed.
D.)The magnetic field would be turned off.

Consider a 1000 w iron whose base plate is made of 0.5 cm thick aluminum alloy 2024-t6 (ρ = 2770 kg/m3 and cp = 875 j/kg°c). the base plate has a surface area of 0.03 m2. initially, the iron is in thermal equilibrium with the ambient air at 22°c. assuming 90% of the heat generated in the resistance wires is transferred to the plate, determine the minimum time needed for the plate temperature to reach 200°c.