A bimetallic strip is made of aluminium and steel $\left(\alpha_{\mathrm{Al}}>\alpha_{\text {steel…
A bimetallic strip is made of aluminium and steel $\left(\alpha_{\mathrm{Al}}>\alpha_{\text {steel }}\right)$. On heating, the strip will
remain straight
get twisted
bend with aluminium on concave side
bend with steel on concave side
Solution
As we know that,
$
\begin{array}{rlrl}
\Delta l & =l_0 \alpha \Delta T \\
\Rightarrow & \alpha & =\frac{\Delta l}{l_0 \Delta T}
\end{array}
$
where, $\Delta l$ is change in length, $l_0$ is initial length,
$\Delta T$ is change in temperature and $\alpha$ is coefficient of linear expansion.
Now,
$
\begin{array}{ll}
\because & \alpha_{\mathrm{Al}}>\alpha_{\text {stecl }} \\
\therefore & \Delta l_{\text {Al }}>\Delta l_{\text {stecl }}
\end{array}
$
That means aluminium expands more than steel.
