A metre scale made of steel is to be so graduated that at any temperature a reding of 1 mm should be correct up to 0.0005 mm. What can be the maximum allowed change in temperature while marking the millimetre gaps? Coefficient of linear expansion of steel `=13.22 times 10^(-6@)C^(-1).`

Explanation

Suppose while marking the millimetre gaps, the maximum change in temperature allowed is `deltat.` If the temperature increases, then at the maximum temperature, the value of 1 mm will be 1+0.0005 = 1.0005 mm.
`therefore " " 1.0005=1+alpha*deltat=1+13.22 times 10^(-6) times deltat`
or, `" " deltat=0.0005/(13.22 times 10^(-6))=37.82^(@)C.`