Explain some uses of electromagnets and temporary magnets.

Uses of Electromagnets and Temporary Magnets

1. Uses of Electromagnets:

Electromagnets are temporary magnets that are created by passing an electric current through a coil of wire, often wrapped around a ferromagnetic core (such as iron). The strength of the electromagnet can be controlled by adjusting the current or the number of turns in the coil. Since electromagnets can be turned on and off, they are widely used in various applications where this feature is crucial.

Here are some of the key uses of electromagnets:

1. In Electric Motors and Generators:

   • Electric Motors: Electromagnets are a fundamental part of electric motors. They are used to create rotational motion by interacting with permanent magnets or other electromagnets within the motor.
   • Generators: Electromagnets are also used in electric generators to convert mechanical energy into electrical energy by rotating the electromagnet within a magnetic field.

2. Magnetic Lifting Devices:

   • Electromagnets are used in cranes to lift heavy metal objects, such as scrap iron or steel, in industries like recycling, construction, and shipping. When the electromagnet is activated, it attracts metal objects; when turned off, the objects can be released.

3. Magnetic Resonance Imaging (MRI):

   • Electromagnets are crucial components of MRI machines, which are used in hospitals for medical imaging. The powerful magnetic field produced by the electromagnet is used to align the protons in the body, helping to create detailed images of internal structures, like the brain, muscles, and organs.

4. Magnetic Relays:

   • Electromagnets are used in relays, which are electrical switches that can control the flow of electricity in circuits. They are widely used in telecommunications, computers, and automated systems.

5. Speakers and Microphones:

   • Electromagnets are used in speakers to convert electrical signals into sound. A current is passed through a coil, creating a magnetic field that interacts with a diaphragm to produce sound. Similarly, in microphones, a moving coil within a magnetic field converts sound into electrical signals.

6. Electromagnetic Induction:

   • Electromagnets are used in devices that rely on electromagnetic induction, such as transformers and inductors, which are essential in power transmission and electronic circuits.

7. Magnetic Locks:

   • Electromagnets are used in magnetic door locks (also known as maglocks), where a strong magnetic field secures a door. The door can be unlocked by breaking the electrical circuit, which disables the magnetic field.

8. Electric Bells:

   • In electric bells, an electromagnet is used to attract a striker and produce sound. When the current is passed through the coil, the electromagnet attracts the striker to hit a bell.

2. Uses of Temporary Magnets:

Temporary magnets are materials that become magnetized in the presence of an external magnetic field, but lose their magnetism once the field is removed. While they are not as durable as permanent magnets, they still have significant uses due to their ability to be magnetized and demagnetized quickly.

Here are some common uses of temporary magnets:

1. Electromagnets (as mentioned above):

   • As temporary magnets, electromagnets play a significant role in various applications where the ability to control the magnetization is important (such as in electric motors, generators, and magnetic cranes).

2. Magnetic Tools:

   • Temporary magnets are used in magnetic tools, such as magnetic screwdrivers and magnetic picks. These tools use temporary magnetism to hold small metal objects, such as screws or nails, to the tool while working.

3. Magnetic Separators:

   • Temporary magnets are used in magnetic separators, which are employed to separate magnetic materials from non-magnetic materials in industries like mining, recycling, and food processing.

4. Television and Computer Monitors:

   • Cathode ray tube (CRT) monitors used temporary magnets to deflect the electron beam in a controlled way, directing it to specific points on the screen to create images. However, modern LCD/LED screens have replaced CRTs.

5. Magnetic Field Shielding:

   • Temporary magnets are used in shielding devices to protect sensitive equipment from external magnetic fields. Soft iron is commonly used in this application because it can be magnetized temporarily to divert or absorb the magnetic field.

6. Magnetic Levitations and Suspension:

   • In magnetic levitation (maglev) trains, temporary magnets are used for suspension and movement. A system of electromagnets (temporary magnets) is used to levitate the train and allow it to move without touching the tracks, providing high-speed transport.

7. Magnets for Inducing Magnetism:

   • Temporary magnets are often used in laboratories and educational settings to demonstrate induced magnetism. For example, rubbing a steel nail with a magnet induces temporary magnetism in the nail, which then acts as a temporary magnet.

8. Magnetic Clutch:

   • A temporary magnet is sometimes used in magnetic clutches, which engage or disengage mechanical systems using magnetic fields. These systems are used in automobile engines and various industrial machines to control power transmission.