What effect would increasing the number of loops in a coil of a wire have on an electromagnet

Increases the magnetic field strength

Explanation:

When electrical current is passed through a coil, it creates a magnetic field like a magnet. As the current keeps going, it generates north pole and south pole at both ends of the magnet. If the wire is continuous or probably long enough, its possible to generate a larger magnetic field as long as electric current is still passing through it. Increase in the length of the coil or wire leads to increase in the magnetic field strength.

E = BILsinlΘ

where b = magnetic field intensity

I = current passing through the coil

L = Length of the wire.

From the above equation, increase in length would definitely lead to increase in the magnetic field strength likewise decrease in the length would give a decrease in magnetic field strength.

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current

the answer would be a