The volume of mercury in the bulb of a thermometer is $ {{10}^{-6}}{{m}^{3}} $ . The area of cross- section of the capillary tube is $ 2\times {{10}^{-7}}{{m}^{2}}. $ If the temperature is raised by $ 100{}^\circ C $ , the increase in the length of the mercury column is $ \left( {{\gamma }_{Hg}}=18\,\times \,{{10}^{-5}}{{/}^{0}}C \right) $