# NCERT Class 11 Physics Solutions: Chapter 11 – Thermal Properties of Matter-Part 4 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 11.9:

A brass wire long at is held taut with little tension between two rigid supports. If the wire is cooled to a temperature of , what is the tension developed in the wire, if its diameter is Co-efficient of linear expansion of brass Young՚s modulus of brass

Initial temperature,

Length of the brass wire at

Final temperature,

Diameter of the wire,

Tension developed in the wire

Coefficient of linear expansion of brass,

Young՚s modulus of brass,

Young՚s modulus is given by the relation:

Tension developed in the wire

Area of cross > section of the wire.

Change in the length, given by the relation:

Equating equations we get:

Hence, the tension developed in the wire is

Question 11.10:

A brass rod of length and diameter is joined to a steel rod of the same length and diameter. What is the change in length of the combined rod at , if the original lengths are at ? Is there a ‘thermal stress’ developed at the junction? The ends of the rod are free to expand (Co-efficient of linear expansion of brass ) .

Initial temperature,

Final temperature,

Change in temperature,

Length of the brass rod at

Diameter of the brass rod at

Length of the steel rod at

Diameter of the steel rod at

Coefficient of linear expansion of brass,

Coefficient of linear expansion of steel,