The Total solution for NCERT class 6-12
T = 27 °C
At the temperature of 27 °C the length of the tape is 1m =100 cm
T1 = 45°C
At the temperature of 45 °C the length of the tape is 63 cm
Coefficient of linear expansion of steel = 1.20 × 10–5 K–1
Let L be the actual length of the steel rod and L’ is the lengthat 45 °C
L’ = L [1 + ∝(T1 – T)]
= 100 [1+ 1.20 × 10–5 (45-27)]
= 100[1+ 21.6 × 10–5]
= 100 + 2160 x 10–5
= 100 + 0.02160 = 100.02160
The actual length of the rod at 450 Cis
L2 =(100.02160 /100) x 63 = 63. 013608 cm
The length of the rod at 270 Cis 63.0 cm