11. In the previous problem, a copper foil of density 8.9 g/cm, atomic weight 63.6 and thick- ness 1.0 x 105 cm is used instead of gold. When = 10 we get 820 counts per hour. Find the atomic number of copper. 12. Prove that Planck's constant has the dimensions of angular momentum. 11. In the previous problem, a copper foil of density 8.9 g/cm, atomic weight 63.6 and thick- ness 1.0 x 105 cm is used instead of gold. When = 10 we get 820 counts per hour. Find the atomic number of copper. 12. Prove that Planck's constant has the dimensions of angular momentum.