An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. It consists of a solenoid (wire) wrapped around a bar of iron or other ferromagnetic material. A solenoid is a coil of wire with electric current flowing through it. This gives the coil north and south magnetic poles and a magnetic field. The magnetic field of the solenoid magnetizes the iron bar and creates a more powerful magnet. Electromagnets are used as components of other electrical devices as well as in industry to lift or move heavy objects. Which of these would not increase the strength of an electromagnet?
A) adding more coils of wire
B) using a larger magnetic core
C) increasing the current flowing through it
D) increasing the distance between the wire and the core

An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. It consists of a solenoid (wire) wrapped around a bar of iron or other ferromagnetic material. A solenoid is a coil of wire with electric current flowing through it. This gives the coil north and south magnetic poles and a magnetic field. The magnetic field of the solenoid magnetizes the iron bar and creates a more powerful magnet. Electromagnets are used as components of other electrical devices as well as in industry to lift or move heavy objects. Which of these would not increase the strength of an electromagnet?

A) adding more coils of wire

B) using a larger magnetic core

C) increasing the current flowing through it

D) increasing the distance between the wire and the core

It's too short. Write at least 20 characters to explain it well.

D

fgravity=10x10=100n case 1

fgravity=30x20=600n case 2

6 times more