Voltage - General Physcis - Lecture Slides, Slides of Physics

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Voltage

Volt

The electric potential is relatedto the potential energy.

•^

Compare to test charge

The unit of electric potential isthe volt (V).

•^

1 V = 1 J/C

q q U

V

 



q

d F

E

 V

Electric Work

A cathode ray tube accelerateselectrons across a potential of20 kV. Find the speed of theelectrons at the screen.

The potential can be convertedto an energy.

•^

qV

= (1.6 x 10

C)(2 x 10

(^4)

V)

= 3.2 x 10

J.

The potential energy becomeskinetic energy.

•^

qV

mv

2

Solve for the speed

v

•^

v^

= 8.4 x 10

7 m/s

Uniform Field

A uniform electrical field hasthe same magnitude anddirection at all points.

A charge moving parallel tothe field lines changespotential by

V = Ed

A charge movingperpendicular to the fieldlines has no change inpotential.

qEd^ q

U

 

q

d F

E

 U

Ed

V

 

Voltage Source

A voltage source is called a^ battery

A battery attached to aconducting plate places thesame potential across theplates.

A uniform electric field existsbetween the plates.





Internal Field

A 12-V source is connected toparallel plates 2.0 mm apart.Find the magnitude of the fieldbetween the plates.

The relationship between thefield and voltage is

V = Ed

•^

Solve for

E = V/d

The field is

E

(12 V) / (0.002 m) = 6.0 kV/m.





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