What is linear expansivity?​will receive brainliest if answered correctly​

Linear expansivity is the fractional increase in length of a specimen of a solid, per unit rise in temperature. If a specimen increases in length from l1 to l2 when its temperature is raised θ°, then the expansivity (α) is given by: l2 = l1(1 + αθ). This relationship assumes that α is independent of temperature. This is not, in general, the case and a more accurate relationship is: l2 = l1(1 + aθ + bθ2 + cθ3…), where a, b, and c are constants.

l2 = l1(1 + αθ).

l2 = l1(1 + aθ + bθ2 + cθ3…),

Linear expansivity is the fractional increase in length of a specimen of a solid, per unit rise in temperature. ... Superficial expansivity is the fractional increase in area of a solid surface caused by unit rise in temperature, i.e. A2 = A1(1 + βθ), where β is the superficial expansivity.

I hope it's helpful!

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