The laser pointer emits light because electrons in the material are excited (by a battery) from their ground state to an upper excited state. when the electrons return to the ground state, they lose the excess energy in the form of 545-nm photons. what is the energy gap between the ground state and excited state in the laser material?

Abeverage can is made of 3004-h19 aluminum alloy (elastic modulus 69 gpa, tensile yield strength 285 mpa, density 2.72 g/cm^3). the dimensions on the can are approximated as a thin-walled cylinder with a height of 4.83 inches, diameter of 2.60 inches. empty the can has a mass of 14.2 g. determine: a. the wall thickness of the cylinder b. assuming a pinned-pinned condition what is the critical load? c. assuming a fixed-fixed condition what is the critical load?