!Please help fast!!*18 pts*! How is light amplified in a laser?
A. Photons "leak" through a partically reflecting mirror, causing them to travel in step.
B. Integrated circuits in a laser amplify the sound produced by photon emission.
C. Photons collide with gas particles, multiply, and reflect back and forth in a tube.
D. Electric current is amplified and directed into gas particles, which emit photons.

A.

Explanation:

Some of these photons are absorbed by the atoms in the ground state and the photons are lost to the laser process. However, some photons cause stimulated emission in excited-state atoms, releasing another coherent photon. In effect, this results in optical amplification

a high pressure system is a dense air mass that is usually cooler and drier than the surrounding air. a low pressure system is a less dense air mass that is usually wetter and warmer than the surrounding air.

in general, areas that experience high atmospheric pressure also experience fair weather. low pressure systems can cause the formation of clouds and storms. air usually flows from areas of high pressure to areas of low pressure..

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.