This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: ASSIGNMENT 3 21.4.I DENTIFY : Use the mass m of the ring and the atomic mass M of gold to calculate the number of gold atoms. Each atom has 79 protons and an equal number of electrons. S ET U P : 23 A 6.02 10 atoms/mol N = . A proton has charge + e . E XECUTE : The mass of gold is 17.7 g and the atomic weight of gold is 197 g mol. So the number of atoms is 23 22 A 17.7 g (6.02 10 atoms/mol) 5.41 10 atoms 197 g mol N n = = . The number of protons is 22 24 p (79 protons/atom)(5.41 10 atoms) 4.27 10 protons n = = . 19 5 p ( )(1.60 10 C/proton) 6.83 10 C Q n- = = . (b) The number of electrons is 24 e p 4.27 10 . n n = = E VALUATE : The total amount of positive charge in the ring is very large, but there is an equal amount of negative charge. 21.26. I DENTIFY : For a point charge, 2 q E k r = . S ET U P : E r is toward a negative charge and away from a positive charge. E XECUTE : (a) The field is toward the negative charge so is downward. 9 9 2 2 2 3.00 10 C (8.99 10 N m /C ) 432 N/C (0.250 m) E- = = . (b) 9 2 2 9 (8.99 10 N m /C )(3.00 10 C) 1.50 m 12.0 N/C k q r E- ״ = = = E VALUATE : At different points the electric field has different directions, but it is always directed...
View Full Document