A spectrograph is used to:

A: see radio waves
B: analyze infrared and ultraviolet rays
C: measure distance
D: photograph the light spectrum

the answer is D because it gets the spectrum of light

if the thermos has a vacuum innner, then heat through conv currents and conduction are reduced = vacuum flask

firearm identification is the process of analyzing the bullets and cartridge cases left at a crime scene to determine if they came from a particular firearm. marks on the bullets and cartridges may be common to every firearm of that type. these are called class characteristics.