Question

The ratio of lengths of two rods of different materials is taken as 2 : 3such that the difference of their lengths is 10 cmat all
temperatures. The length of the rod of lesser expansion is​

Answer 1

Answer:

The rate of heat flow in a rod of length l , is given by ,

Q/

where A= cross- sectional area of rod ,

s of rod ,

now given that ratio of lengths of two rods =1:2 ,

let their lengths are l

1

=L , and l

2

=2L respectively ,

and given that ratio of radii of two rods =2:3 ,

let their radii are r

1

=2r , and r

2

=3r respectively ,

hence , their cross-sectional areas are A

1

=2π(2r)

2

and A

2

=2π(3r

and rate of heat flow in a rod of length 2L is ,