An iron rod of length 50cm is joined at an end to an aluminium rod of length 100cm. All measurements refer to 20°C…

Q: An iron rod of length 50cm is joined at an end to an aluminium rod of length 100cm. All measurements refer to 20°C. The coefficients of linear expansion of iron and aluminium are 12 × 10-6/°C and 24 × 10-6/°C , respectively. The average coefficient of composite system is

(a) 36 × 10-6/°C

(b) 12 × 10-6/°C

(c) 20 × 10-6/°C

(d) 48 × 10-6/°C

Ans: (c)