Q.

The temperature of a metal strip having coefficient of linear expansion α is increased from T1 to T2 resulting in increase of its length by ΔL1. The temperature is further increased from T2 to T3 such that the increase in its length is ΔL2.

Given T3+T1=2T2 and T2-T1=ΔT, the value of ΔL2 is ______.             [2026]

1 ΔL1[1+2α2(ΔT)2]  
2 ΔL1[1+α2(ΔT)2]  
3 ΔL1[1+2αΔT]  
4 ΔL1[1+αΔT]  

Ans.

(4)

ΔL1=αL1ΔT

ΔL2=(L1+ΔL1)(T3-T2)

ΔL2=(L1+ΔL1)ΔT

ΔL2=(ΔL1αΔT+ΔL1)αΔT

ΔL2=ΔL1[1+αΔT]