You must have noticed magnets at one point of time in your life. But do you know that these magnets play crucial roles in our daily lives? Well, in this article, we’ll discuss some everyday examples of magnets and the magnetic force produced by them. Before moving ahead, let’s have some basics about the magnetic force.
What is a Magnetic Force?
The magnetic force is a part of the electromagnetic force, one of the four fundamental forces of nature, and is caused by the motion of charges. There will be a magnetic attraction force between two objects containing charge with the same direction of motion, whereas, objects with charge moving in opposite directions have a repulsive force between them. It can also be defined as the attractive or repulsive form of energy that exists between the poles of a magnet and electrically charged moving particles. These moving charges create magnetic fields, and the interacting magnetic fields give rise to magnetic force.
Types of Magnetic Force
Magnetic force can be of following types:
Diamagnetism- Diamagnetic materials have no unpaired electrons. Almost every material possess diamagnetism and these materials have the tendency to oppose an applied magnetic field, and therefore, these are repelled by a magnetic field. Examples- Copper, Silver, Gold, Air, Water, etc.
Paramagnetism– Paramagnetic materials have unpaired electrons. As an unpaired electron is free to align its magnetic moment in any direction; in the presence of an external magnetic field, these magnetic moments tend to align themselves in the same direction as the applied field, thus, reinforcing it. Examples- Aluminium, Manganese, Platinum, Lithium, Oxygen, etc.
Ferromagnetism– Like paramagnetic materials, these also have unpaired electrons. Ferromagnetic materials are strongly magnetized in an external magnetic field and retain their magnetic property even after the removal of the external magnetic field. Examples- Iron, Nickel, Cobalt, etc.
How to calculate the magnetic force?
Let’s consider two objects. The magnitude of the magnetic force between them depends on the amount of charge and motion present in each of the two objects and how far apart they are. The direction of the force depends on the directions of motion of the charge.
The force that a magnetic field exerts on a charge (q) moving with velocity (v) is called the magnetic Lorentz force. It is given by:
F = qv × B
Here; ‘B’ is the magnetic field, ‘v’ is velocity, ‘F’ is the force that is perpendicular to the direction of the magnetic field B, and ‘q’ is the charge. F is perpendicular to the plane that contains both v and B.
Examples of Magnetic Force
A compass is a tool for finding direction. It has a magnetic needle mounted on a pivot or short pin. The needle can spin freely, and always points north. Have you ever been on a hiking or camping trip? If you did, then, at some point you must have used a compass to help find your way; because a compass always points North. But have you ever wondered why is it so? Well, it’s all caused by the power of magnetism!
(ii). MRI Scanners
Magnetic resonance imaging (MRI) is one of the most common medical imaging techniques used at many diagnostic centers across the world. These MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body.
(iii). Electric Motor
Ever wondered how Hand-held hair dryers, electric knives, electric razors, hair, and beard trimmers work? It’s all with the help of Magnetic force. An electric motor converts electrical energy into physical movement. Electric motors generate magnetic fields with electric current through a coil. The magnetic field then causes a magnetic force with a magnet that causes movement or spinning that runs the motor.
Ever wondered how a speaker works? In order to convert an electrical signal into an audible sound, speakers contain an electromagnet (a metal coil that creates a magnetic field when an electric current flows through it). This means that it is, in turn, attracted to and repelled from the permanent magnet, vibrating back and forth.
Have you wondered how the refrigerator functions? How the refrigerator door remains closed? the weak ferromagnetic ceramics like barium ferrite or strontium ferrite present in the fridge magnet aligns the spins of unpaired electrons in metal atoms in the fridge in such a way that the magnet and the fridge door are attracted to each other; this force keeping the doors closed.
Well, data are stored in hard disk drives on the basis of magnetism. There’s a coating of magnetic material on the disc; consisting of billions or even trillions of tiny magnets. With the use of an electromagnetic head, data is stored in the disc.
Microwave ovens also work with the help of the magnetic force. They use a device called a magnetron to generate the power for cooking. A magnetron is a vacuum tube designed to cause electrons to circulate in a loop inside the tube. A magnet is placed around the tube to provide the magnetic force that causes the electrons to move in a loop.
We see cars everywhere around us, but have you ever wondered what makes it move from one point to another? It is due to Magnetic force. Cars use electromagnetic properties produced inside the engine to create movement, while with fossil fuel engines, the energy is obtained by the ignition. By turning the magnetic coil attached to an axle, the wheels of the car also turn and the car moves.
Maglev is a system of train transportation that uses two sets of magnets, one set to repel and push the train up off the track, and another set to move the elevated train ahead, taking advantage of the lack of friction. The next you travel by train, you’ll be amazed to be traveling on huge magnets.
The magnets in the rotor of the fan are repelled by those in the stator. As they manage to repel themselves away to the maximum permitted by the movement of the rotor, the electrical circuit switches one of the sets of magnets over, so that those in the rotor and stator find themselves repelling each other again. By doing this repeatedly at each cycle of the rotor, the rotor is kept constantly on the move. All this is done by the power of Magnetic force.
I have a Seiko Kinetic watch and it says not to keep it in proximity to strong magnetic forces.
I keep two Apple iPods and a Bose sound dock for them on my bedside table; are these strong magnetic forces individually or collectively? would it help if I kept my watch in the drawer of the bedside table overnight? Or would this still be too close to the sound dock?