21_Ch 15 College Physics ProblemCH15 Electric Forces and Electric Fields

21_Ch 15 College Physics ProblemCH15 Electric Forces and Electric Fields

This preview shows page 1. Sign up to view the full content.

Electric Forces and Electric Fields 21 (c) Outside the spherical dome, 2 e kq E r = . Thus, at 4.0 m r = , () ( ) 92 2 4 2 8.99 10 N m C 2.0 10 C C 4.0 m E ×⋅ × == 5 1.1 10 N × 15.35 For a uniformly charged sphere, the field is strongest at the surface. Thus, max max 2 e E R = , or ( ) ( ) 2 6 2 3 max max 2 2.0 m 3.0 10 N C 1.3 10 C 8.99 C e RE q k × = × 15.36 If the weight of the drop is balanced by the electric force, then mg or the mass of the drop must be q E eE ( ) ( ) 19 4 16 2 1.6 10 C 3 51 0 k g 9.8 m s eE m g ×× × But, 3 4 3 mV r ρρ π    and the radius of the drop is 13 3 4 m πρ r = 16 7 3 35 10 kg 5.2 10 m or ~ 1 m 48 5 8 k gm rr µ  ×  ×  15.37 (a)
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/09/2011 for the course PHYS 2020 taught by Professor Staff during the Fall '10 term at FIU.

Ask a homework question - tutors are online