Two-metre scales, one of steel and the other of aluminium-centimetre/steel-centimetre at (a) 0°C, (b) 40°C and (c) 100°C. α for steel = 
and for aluminium 
*
a) 
b) 
c) 
Explanation:
Given,
Coefficient of linear expansion
of Aluminium
αAl, is
2.3 ×10-5°C-1
Coefficient of linear expansion of steel, αS, is 1.1 ×10-5°C-1
The scale is calibrated at the reference temperature of 20°C
Formula used 
L0= Length at a reference temperature,
α= coefficient of linear expansion,
θ= Change in temperature.
‘Al’ and ‘S’ will be used as subscripts to denote Aluminium and Steel respectively.
a) at 0°C
b) at 40°C
c) at 100°C
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