Four rods with different raddi r and length l are used to connect two heat reservoirs at different temperatures . Which one will conduct most heat ?

Options

A. r=1cm,l=1m
B. r=1cm,`l=(1)/(2)m`
C. r=2cm,l=2m
D. r= 2 cm,`l=(1)/(2)m`

Answer

d

Explanation

Rate of heat conduction through a rod of radius r and length l,
`(dQ)/(dt)=k((pir^(2)))/((T_(2)-T_(1)))`
for given K and `(T_(2)-T_(1)),frac(dQ)(dt)proptofrac(r^(2))(l)`
Hence, rod With r=2cm and l=`frac(1)(2)` m will conduct most heat.