Question

Which of the following is used to make permanent magnets?
A. Alnico
B. Steel
C. Iron
D. Brass

Answer 1

Hint: A magnet is an item or substance producing a magnetic field. This magnetic field, which is invisible, is responsible for the greatest feature of the magnet, a force which attracts or repels other magnets, such as iron, steel, nickel, cobalt, etc.

Complete answer:
A permanent magnet is an item constructed of a magnetised substance that produces its own magnet field. A refrigerator magnet is a daily example that holds notes on the door of a refrigerator. Steel is used to manufacture the permanent magnet, since the domain changes form when the steel bar is magnetised, due to the reorientation of the dipole in parallel axes and in the same direction and the reorientation of the dipoles in the domain is constant.

Therefore, when magnetised, steel has permanent magnetism. When magnetised but separated from the origin of the induced magnetism, the iron bar, too, disrupts and disputes the repulsive strength between the parallel dipoles. Therefore, the bar of iron lost magnetic. Thus, iron briefly preserves the magnetic. Alnico is a class of iron alloys made mostly of aluminium, nickel and cobalt in addition to iron, and is hence an al-ni-co acronym. Copper and titanium are also included.

Alnico alloys are ferromagnetic and are utilised for the production of continuous magnets. Mainly composed of aluminium, Nickel, and Cobalt combinations but may also include Copper, Iron, and Titanium, Alnico magnets are permanent magnets. The isotropic or anisotropic variants are offered with an alnico magnet.

Hence option A and B is correct.

Note:Typically the composition of alnico alloys is 8 to 12% Al, 15 to 25% Ni, 5 to 24% Co, up to 6% Cu, up to 1% Ti, and the remainder is Fe. Alnico began its development in 1931 when T. Mishima found in Japan that iron, nickel and aluminium alloys possessed a coercive strength of 400 kA/m (32 kA/m), double the number of top magnet steels of the time.