Category: Classical Physics
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The Fundamentals of Electromagnetic Waves
Electromagnetic waves are electric and magnetic fields traveling through free space at the speed of light; in other words, an electromagnetic wave is a propagating electromagnetic field that travels with finite velocity as a disturbance through a medium. The field itself is the disturbance, rather than simply representing a physical displacement or other effect on…
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Lightning as an Electrical Phenomenon
Friction produces electric charges high in the atmosphere. This occurs when small particles such as water droplets and ice collide or rub against one another. Wind, among other factors, separates these charges and large electric forces develop between the ground and the air above. The atmospheric charges and fields have strong effects. Opposite charges attract…
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The Principle & Application of Nuclear Magnetic Resonance (NMR)
Nuclear magnetic moments (along with electronic magnetic moments) precess (spin) when placed in an external magnetic field, B. The frequency at which they precess, called the Lamor precessional frequency, wL, is directly proportional to the magnetic field. When the magnetic moment μ is lined up with the field as closely as quantum physics permits, the…
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The Physics Behind Magnetic Resonance Imaging (MRI)
MRI provides physicians with a tool to assess a patient’s health. To have an MRI exam, the patient lies in a very strong magnetic field that is generated by powerful magnets. The MRI machine then applies radio waves to the patient’s body; radio waves are electromagnetic waves. MRI uses radio waves as this kind of…
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The Operation of Magnetically Levitated Trains (Maglevs)
Magnetic levitation (maglev), take place when the magnetic interaction is strong enough to balance the force of gravity. The like poles of two magnets repel one another, and if the magnets are placed vertically and the strength of the repulsion is the same as the strength of gravity, the net force is zero. The magnet…
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Newton’s Law of Universal Gravitation
Newton’s law of universal gravitation is a physical law that states that every particle attracts every other particle in the universe with the force of attraction directly proportional to the product of the masses and inversely proportional to the square of the distance between them. In other words, given any two objects A and B,…
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Basic Facts about Superconductors
Most of the conductors we use in our daily life are metals such copper wire. While these conductors are useful in many applications, they are not perfect as they have at least a small amount of resistance, which implies that some of the current is wasted. However with a special type of conductor (superconductor), this…
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Coulomb’s Law and Electric Field
According to Benjamin Franklin, we have two types of electric charges i.e. positive and negative charges. Positive and negative charges attract, but positive charges repel each other, as do negative charges. The force F that a pair of electric charges Q1 and Q2, separated by a distance r, exert on one another is given by…
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Uses of Static Electricity
Even though static electricity can be unsafe, it has some uses as discussed below: Electrostatic induction can also be applied to spread paint evenly on a surface. Tiny droplets of paint, when given the same charge, repel one another. When sprayed on a surface, such as the body of a car, the paint forms a…
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Newton’s Laws of Motions
Before Einstein, physicists believed that the behaviour of almost everything was controlled by three rules called “Newton’s Laws of Motion”. The basic point was to relate the motion of objects to the “forces” that act on that object. These forces picked out certain reference frames as special (Inertial frames). Newton’s First Law of Motion This…