Month: October 2023
-
What are Atom Traps?
Atoms that are cooled below a millikelvin can also be held in space with either static magnetic fields, laser fields, or a combination of a weak magnetic field and circularly polarized light. Atoms traps can be used to accumulate a large number of laser-cooled atoms; confine them for further cooling and use them for studies…
-
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…
-
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…
-
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…
-
The Bending of Starlight as Predicted by Einstein
Light falls in a gravitational field, for instance, a laser beam fired horizontally across a room will be closer to the ground on the side where it hits the far wall than it was when it left the laser. Likewise, a ray of light that is passing over a massive object like the sun will…