Which of the following circular rods, (given radius r and length l) each made of the same material and whose ends are maintained at the same temperature will conduct most heat?
a) r = 2r₀; l = 2l₀
b) r = 2r₀; l = l₀
c) r = r₀; l = 2l₀
d) r = r₀; l = l₀

Explanation:

Heat flow in a circular rod is given by

where Q= heat flow

k=thermal conductivity

A=area of cross-section

dT=Change in temperature

dx=change in length

Also A can be written as

thus Q is Proportional to

For option (a)

(b)

(c)

(d)

So Rod b will conduct the most Heat

answer: a. same unit

explanation:

the answer is false. this is because for ice to melt, it requires latent heat of melting. latent heat means heat energy required to change phase without any increase in temperatures. therefore, the ice will take energy from the environment to melt hence atmospheric temperatures will reduce.