Conduction of Heat: a Cylindrical Bar That Is Well Insulated

Conduction of heat: A cylindrical bar that is well insulated around its sides connects hot and cold reservoirs and conducts heat at a rate of 10.0 J/s under steady state conditions. If all of its linear dimensions (diameter and length) are reduced by half, the rate at which it will now conduct heat between the same reservoirs is closest to

A) 80.0 J/s.
B) 20.0 J/s.
C) 5.00 J/s.
D) 2.50 J/s.
E) 1.25 J/s.