Physics ���Chapter 16: Electric Forces and

Fields ���Chapter 17: Electric Energy and

Current

Section 16.3 Electric Fields

Electric Fields

--Electric forces are field forces, capable of!acting at a distance through space.!

--An electric field is a region around a charged!object where an electric force on a test charge!can be detected.!

--The magnitude and direction of the electric!field is defined as the electric field lines on a!unit positive charge.!

--The field lines will point away from an object!with a positive charge and towards an object!with a negative charge.!

http://qbx6.ltu.edu/s_schneider/physlets/main/efield.shtml

Electric Field Strength --The strength of the electric field can be!

calculated:!

--This equation gives the electric field!strength or the force per unit charge.!

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E = Fc

qo

Since:!

And:! ! qo = q1 = 1 e!

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Fe = Kc q1q2

R2

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E = Kcq

R2Then:!

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E = Kcq

R2

Ex: What is the electric field strength around an object whose charge is +2.5 x 10-10 C at a distance of 0.30 m?!

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E = (8.9875 x 109 N *m2

C2 )( +2.5 x 10-10 C(0.30 m)2 )

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E = 24.96 NC