Question

Magnetic materials over the years have affected our lives greatly in one way or the other, as an engineering materials science student, select an appropriate magnetic material for the following applications and why?:
(i) A High electrical-efficiency motor,
(ii) A Magnetic device to keep cupboard doors closed,
(iii) A Magnet used in an ammeter or voltmeter,
(iv) A Magnetic resonance imaging

Answer 1

1)In high electrical efficiency motor

Magnetic materials are used for the production of permanent magnets to achieve high induction values and to prevent the risk of demagnetisation

Because of permanent magnets DC motor is 30percent more efficient than AC motor

2)magnet keep the door shut and help to form an air tight seel between the door and room

3) in ammeter it uses magnetic deflection, where current passing through coil is placed in the magnetic field of a permanent magnet causes the coil to move

In voltmeter

When an electric current is applied the interaction of the magnetic field of the coil and of the secondary creates a torque tending to make the coil rotate

4) MRI uses large magnet and radio waves to look at organs and structures inside the body