Question

How can an electromagnet be made stronger.
(A) Add more coils of wire.
(B) Add an iron core.
(C) Increase the voltage.
(D) All of these answers are correct.

Answer 1

Hint: An electromagnet can be defined as a magnet which functions on electricity. Electromagnets are made out of a coil of wire (wire curled in series). This is more effective in producing a magnetic field than just a wire running straight. This effect can be strengthened by winding a wire tightly around a powerful core, made of magnetic material, such as iron.

Complete step by step solution:
An electric current has the ability to produce a magnetic field in a plane perpendicular to the direction of current flow. If a soft iron bar is placed inside the solenoid, and the current switched on, the iron bar becomes temporarily magnetized. This is the principle of the electromagnet. Unlike a permanent magnet, the strength of an electromagnet can be changed by changing the amount of electric current that flows through it. If the current flow is cut, the property of magnetism ceases to exist.
 The strength of the magnetic field of an electromagnet increases when:
(a) The current (voltage) is increased. The greater the current, the greater the strength. This because the current increases there is more flow of electrons which in turn increases the magnetic field around it.
(b) The number of turns is increased. The greater the number of coils, the greater the strength. This is because more the number of coils, more uniformity is obtained in the magnetic field and hence it is stronger.
(c) The turns of wire are pushed closer together so that the length of the solenoid becomes shorter.
(d) A soft iron core is placed into the solenoid. Whether the core is made up of a soft or hard magnetic material. Soft iron core magnetizes more quickly than hard magnetic materials like steel.
 (e) Also, the use of alloys such as aluminum-nickel- cobalt (alnico) can produce stronger magnetic fields.
Electromagnets are used in various devices like:
Particle accelerator, amplifier, magnetic separation, electric motor and generators, MRI machines, Control Switches in Relays, Transportation, Spacecraft Propulsion Systems, Induction Heating, Hard Drives and many others.
Electromagnets are used in various devices like:
Particle accelerator, amplifier, magnetic separation, electric motor and generators, MRI machines, Control Switches in Relays, Transportation, Spacecraft Propulsion Systems, Induction Heating, Hard Drives and many others.

Hence option (D) is correct.

Note: Electromagnets have few disadvantages too:
1. They heat up very fast
2. It consumes a lot of energy
3. They can store huge amounts of energy in their magnetic field. If the electric current is interrupted, the energy will discharge.