Question

A bar of iron is 10 cm at 20°C. At 19°C it will be (are = 11 x 10-6/°C)

(1) 11 x 10-6 cm longer
(2) 11 x 10-6 cm shorter
(3) 11 x 10-5 cm shorter
(4) 11 * 10-5 cm longer
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Answer 1

the answer is 3 ( 11 times 10-5 cm longer )

Answer 2

HENCE (3) IS ANSWER

Step-by-step explanation:

α =ΔL/(LO×Δ T) or ΔL= α(LO×Δ T)

HERE ΔL IS CHANGE IN LENGTH, Lo is original length , α is coefficient of linear expansion , Δ T is change in temperature

α= 11 x 10 ^-6/°C , Δ T = 19-20 = -1°C

hence

ΔL= 11 x 10 ^-6×10×-1

= - 11×10^-5

MINUS SIGN SHOWS SHORTER

HENCE (3) IS ANSWER