$A$ thin copper wire of length $L$ increases in length by $1\%$ when heated from temperature $T_1$ to $T_2$. What is the percentage change in area when a thin copper plate having dimensions $2L \times L$ is heated from $T_1$ to $T_2$?

Explain linear expansion. Write its unit.

Two marks on a glass rod $10 \ cm$ apart are found to increase their distance by $0.08 \ mm$ when the rod is heated from $0 \ ^\circ C$ to $100 \ ^\circ C$. $A$ flask made of the same glass as that of the rod measures a volume $1000 \ cc$ at $0 \ ^\circ C$. The volume it measures at $100 \ ^\circ C$ in $cc$ is:

An aluminium sphere of $20 \; cm$ diameter is heated from $0^{\circ} C$ to $100^{\circ} C$. Its volume changes by (given that coefficient of linear expansion for aluminium $\alpha_{Al} = 23 \times 10^{-6} \; /^{\circ} C$): (in $; cm^3$)

Two large holes are cut in a metal sheet. If this sheet is heated,what happens to the distances $AB$ and $BC$ as shown in the figure?

Two rods,one of aluminum and another of steel,have initial lengths $l_1$ and $l_2$ respectively. They are joined together to form a single rod of length $(l_1 + l_2)$. If the coefficients of linear expansion for aluminum and steel are $\alpha_a$ and $\alpha_s$ respectively,and the increase in length for both rods is the same when the temperature of both is increased by $t \ ^\circ C$,then $\frac{l_1}{l_1 + l_2} = \dots$