Question

A scale of steel shows correct reading at 20 degree centigrade. The length of a copper rod is found to be 150 cm at 20 degree centigrade when measured with that scale . If the length of the same rod is measured with the same scale at 60 degree centigrade ,what would be the length of the rod ?
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Answer 1

Answer:

lo is the reading at 20oC.

Let l1 be the scale reading at 20oC which gets aligned with the scale at 40oC.

At 40oC, length of the scale is lo(1+20αc)

The aligned reading on scale is l1(1+20αs)

So lo(1+20αc)=l1(1+20αs)

⇒l1=(1+20αs1+20αc)lo