Tag: Electromagnetism

Quantum Dots for Solar Panels

Quantum Dots for Solar Panels

Quantum Dots for Solar Panels

02/25/19

“Why are quantum dots for solar panels so useful?”

 

Quantum dots are bringing a revolution into the world of semiconductors. And since semiconductors are the backbones of solar panels, things will be greatly changed for them as well. The extra emissivity offered by quantum dots means that two and possibly three electrons can be generated for every photon received, vastly increasing its potential! Quantum dot solar panels can achieve as much as 65% efficiency, nearly double of the theoretical limit of normal panels. This is why Quantum Dots for Solar Panels are so exciting.

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Synchronous Motors

Synchronous Motors

Synchronous Motors

01/01/19

“How can motors be synchronized with current?”

 

AC Motors can convert electrical energy supplied by current into mechanical energy. But are there motors where the frequency of the shaft’s rotation is equal to the frequency of the supply current? Well, it turns out these machines are known as Synchronous Motors and are used in cases where motor speed needs to be very precise.

 

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Op-Amp Feedback

Op-Amp Feedback

Op-Amp Feedback

04/07/18

“How can we control voltage levels using an Op-Amp?”

 

Op-Amps are great for modifying voltage levels in a circuit. But sometimes things happen during the lifespan of an Op-Amp that can affect how it performs. So how can we design these components to self-regulate? Well, what if we were to connect part of the output circuit to the Op-Amp input. Therefore, the voltage levels would be the same as the input, and any change on one side would affect the other. This technique is known as Op-Amp Feedback and is one of the fundamental concepts of modern circuitry.

Electrostatic Precipitators

Electrostatic Precipitators

Electrostatic Precipitators

12/25/17

“How can we remove fine particles from a gas without contact?”

 

When a gas is being transported for use, it often has many fine particles (such as dust and smoke) attached, which can induce health issues. Traditional methods of removing these particles involve using physical barriers to filter out all particles. However, this has the effect of disrupting the flow of the gas. So how can we use our engineering mindset to solve this problem? Well, we know that from fundamental physics that there are two types of forces (contact and distance). And we also know that the latter can be caused by either gravitation, electrical, or nuclear interactions. And these fine particles in the gas are susceptible to become polarized and become at the whim of electromagnetic interaction. So what if we were to simply implement electromagnetic plates perpendicular to the flow of a gas, and suck up all of the fine particles while keeping the gas itself intact? Well, this is the fundamental idea behind Electrostatic Precipitators and are used in industries all around the world.

Magnetic domains, hysteresis, and hard/soft magnets

Magnetic domains, hysteresis, and hard/soft magnets

 

Magnetic domains, hysteresis, and hard/soft magnets

05/22/17

“How do magnetic fields come about and how can we apply this knowledge?”

 

The subatomic interactions in a magnetic object from material properties give rise to its macroscopic phenomena. Magnetic materials are composed of divisions known as magnetic domains that have a random magnetic field direction. When an external magnetic field is applied to a material, all of these domains will align with said field and produce a magnetic force. The magnitude of this magnetic force emanating from the object will be the result of the summation of the magnetic fields from all of the individual domains.

This theory can be applied using a hysteresis loop operates as follows. Take a piece of metal. Now run a coil around it. Generate an AC voltage. At t = 0, there will be magnetic activity in neither the metal nor the coil. When the voltage is increased, it will cause the domains to line up, eventually reaching a maximum value. Now pull the voltage in the other direction. When the voltage is equal to zero, the metal will have some residual magnetic field in it as a result of the shifting domains. If we pull the voltage into a negative state, then eventually it will reach another maximum (at the negative of the original boundary). If we reverse the direction of the current again to zero, then we will also have some residual magnetic field at zero. And if we increase the voltage in the positive direction, then we will reach the maximum again (Schuster, Doc).

 

Based upon their hysteresis profile, a material may be classified into either a hard magnet or a soft magnet. The former has a large profile, and are often used for energy intensive applications such as permanent magnets, while the latter has a smaller profile ideal for use in low energy loss application such as transformers.

Atulasimha, Jatulasimha. “Magnetism.” Magnetism for General Audience. Virginia Commonwealth University, 8 Nov. 2015. Web. 22 May 2017.

 

Callister, William, and David G. Rethwisch.Materials Science and Engineering: An Introduction. 9thed. , John Wiley & Sons, Inc., 2014.

 

Magnetic Hysteresis or I KNOW WHAT YOUR MAGNET DID LAST SUMMER | Doc Physics. Dir. Doc Schuster. Perf. Doc Schuster. Youtube. Doc Schuster, 25 Feb. 2014. Web. 22 May 2017.

Magnetic attraction bearings

Magnetic attraction bearings

Magnetic attraction bearings

04/24/17

“How can we use magnetic attraction to make bearings?”

 

Conventional mechanical bearings are limited by the effects of mechanical friction which impinges their durability, speed, and control. However, by removing physical contact with the shaft, the bearing will become far more optimal. So how could we implement such an idea into reality? Well, one method is to use the physical mechanism of magnetic attraction to remotely control the bearings. Such magnetic attraction bearings would be freed from the limitations of traditional mechanisms and could provide for far more efficiency. However, due to chaotic nature of rotation, a self-centering device must be used with such mechanisms, so that no side becomes too close to the magnetic center and therefore lose balance. Such conundrums can be remedied with magnetic repulsion models.

Magnetic repulsion bearings

Magnetic repulsion bearings

Magnetic repulsion bearings

04/16/17

“Can we use magnetism to improve bearings?”

 

Normal bearings use mechanical forces to lock onto a rotor. However, this method can be made highly inefficient due to heat and frictional losses resulting from contact. However, can we use our engineering mindset to improve this system? Well, to start, let’s look at the root of the problem, the mechanical contact. If we remove this feature, then our system can work with much fewer impingements. One way to create a non-contact grip is to use a magnetic force. So what if we made bearings that make use of magnetic levitation technology to keep in contact? Well, this is the exact idea behind magnetic repulsion bearings, which use a repulsive force to achieve passive levitation. Not only does the repulsion effect keep the bearing afloat, but it also introduces a self-centering mechanism, so if one part becomes to close it will be repelled away.