Two collinear, short, metallic rods of the same diameter are in contact. The top of the upper rod is electrically heated, and the bottom of the lower rod is cooled with a fluid. The exposed surface of the rods are thermally insulated from the surroundings. Which rods have the smallest thermal contact resistance?
a.) Copper rods with smooth surfaces
b.) Copper rods with rough surfaces
c.) Carbon steel rods with smooth surface
d.) Carbon steel rods with rough surfaces

Match each vocabulary term to its definition. 1. electrons neutral subatomic particles found in the nucleus of the atom 2. neutron lowest energy position of an electron in an atom 3. photon the path of an electron around the nucleus of an atom 4. ground state negatively charged, subatomic particles 5. protons packet of energy of specific size 6. element substance with only one type of atom 7. orbital positively charged, subatomic particles found in the nucleus of the atom