Which combination of a wire coil and a core would make the strongest electromagnet?

A. 200 coils of bare wire around a hollow cardboard core

B. 200 coils of insulated wire around a steel bolt

C. 50 coils of insulated wire around a hollow cardboard core

D. 50 coils of bare wire around a steel bolt

When applying kirchhoff's rules, one of the essential steps is to mark each resistor with plus and minus signs to label how the electric potential changes from one end of the resistor to the other. the circuit in the drawing contains four resistors, each marked with the associated plus and minus signs. however, one resistor is marked incorrectly. which one is it?

Science and technology are interdependent. advances in one lead to advances in the other. give an example of this phenomenon.

What can you increase the strength of an electromagnet by