A crystal has linear coefficient of expansion  9×10−5,12×10−5,7×10−5/K along three mutually perpendicular directions the volume expansion coefficient is

coefficient of volume expansion of crystal is γ=αx+αy+αz αx,αy,αz coefficient of linear expansion of crystal along mutually perpendicular directions γ=9×10−5+12×10−5+7×10−5 γ=28×10−5/K