A steel tape is calibrated at $20^{\circ} C$. On a cold day when the temperature is $-15^{\circ} C$, percentage error in the tape will be ........... $\%$ $\left[\alpha_{\text {steel }}=1.2 \times 10^{-5}{ }^{\circ} C ^{-1}\right]$

The coefficient of linear expansion of a crystalline substance in one direction is $2 \times 10^{-4} /{ }^{\circ} C$ and in every direction perpendicular to it is $3 \times 10^{-4} /{ }^{\circ} C$. The coefficient of cubical expansion of crystal is equal to ........... $\times 10^{-4} /{ }^{\circ} C$

A brass wire $1.8\; m$ long at $27\,^{\circ} C$ is held taut with little tension between two rigid supports. If the wire is cooled to a temperature of $-39\,^{\circ} C ,$ what is the tension developed in the wire, if its diameter is $2.0 \;mm$ ? Co-efficient of Itnear expansion of brass $=2.0 \times 10^{-5}\; K ^{-1} ;$ Young's modulus of brass $=0.91 \times 10^{11} \;Pa$

Suppose there is a hole in a copper plate. On heating the plate, diameter of hole, would

A vertical column $50$ $cm$ long at $50°C$ balances another column of same liquid $60 \,cm$ long at $100°C$. The coefficient of absolute expansion of the liquid is

The coefficient of linear expansion of crystal in one direction is ${\alpha _1}$ and that in every direction perpendicular to it is ${\alpha _2}$. The coefficient of cubical expansion is