Answer:
270°C
Step-by-step explanation:
Since αB > αI
We want LB - LI = 0.02 cm at a given temperature t
But
ΔLB= LBαBΔt
ΔLI = LIαIΔt
Where;
LI = length of the iron
LB= length of he brass
αB = Linear expansivity of brass
αI = Linear expansivity of iron
Δt = Change in temperature
ΔLB - ΔLI = (LBαB - LIαI)Δt = 0.02
LB = LI = 12 cm
Δt = 0.02/12( 2.0×10^-5 - 1.32×10^-5)
Δt = 0.02/12(0.68 ×10^-5)
Δt = 245°C
25°C + 245°C = 270°C