Electrostatic Formulas

Chapter 12 - Electrostatics Prepared By: Ali Dodhy Army Public College 0300-7124530

Formulas Symbols Units and Constants Formulas

r q1 q2 1. Fe = k rˆ r2 1 2. k = 4πε o r 1 q1 q2 3. Fe = rˆ 4πε o r 2 r

4. Fe = 5.

1

q1 q2

4πε oε r

r2

r r E=F

qo r 1 q 6. E = rˆ 4πε o r 2 r r 7. φe = E . A 8. φe = EA cos θ q 9. φe =

εo

10.

φe =

Q

εo

Q = q1 + q2 + q3........ + qn

σ rˆ 2ε o r σ E = rˆ εo r

11. E = 12.

13. ∆U = WAB

W 14. ∆V = AB qo

rˆ

∆U qo r ∆V E=− ∆r 1 q V= rˆ 4πε o r ∆K .E = e∆V mgd q= V Q = CV Aε Cvac = o d Aε oε r Cmed = d

15. ∆V = 16. 17. 18. 19. 20. 21. 22.

Cmed Cvac = ε r 1 2 24. Energy = CV 2 1 2 25. Energy = ε oε r E ( Ad ) 2 1 2 26. Energy Density = ε oε r E 2

Symbols r • Fe Electrostatic Force • k coulomb's constant • ε o permitivity of free space

• ε r relative permitivity

r

• E Electric field • φe Electric flux

• σ surface charge density

• U Electric Potential energy • V Electric Potential difference • C Capacitance • F Farad Constants

23.

Prepared By: Ali Dodhy Army Public College

27. F = 6πη rvt

4 m = π r3ρ 3 9η vt 2 29. r = 2ρ g 28.

• k = 9 ×10 Nm C 9

2

−2

• ε o = 8.85 × 10 −12 N −1m −2C 2 Units • • • • • • • • •

r Fe (N)

k (Nm 2C −2 ) ε o (N -1m -2C 2 ) r E ( N C) φ (Nm 2C −1 ) ∆U (J) ∆V (JC-1 ) ∆V (V) C (F)

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