Fields 3: Electric Potential Energy. How does electric potential energy compare to gravitational...
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Transcript of Fields 3: Electric Potential Energy. How does electric potential energy compare to gravitational...
Fields 3: Electric Potential Energy
How does electric potential energy compare to gravitational potential energy?
• A gravitational field acts between two masses– Work done against a gravitational field
• Increases PE
– Work done by a gravitational field• Decreases PE
How does electric potential energy compare to gravitational potential energy?
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• An electric field acts between two charges– Work done against an electric field
• Increases PE
– Work done by an electric field• Decreases PE
For each of the following: does PE increase or decrease?
• Opposite charges are brought together:
For each of the following: does PE increase or decrease?
• Opposite charges are brought together: Decrease• Like charges are moved apart:
For each of the following: does PE increase or decrease?
• Opposite charges are brought together: Decrease• Like charges are moved apart: Decrease• Like charges are brought together:
For each of the following: does PE increase or decrease?
• Opposite charges are brought together: Decrease• Like charges are moved apart: Decrease• Like charges are brought together: Increase• Opposite charges are moved apart:
For each of the following: does PE increase or decrease?
• Opposite charges are brought together: Decrease• Like charges are moved apart: Decrease• Like charges are brought together: Increase• Opposite charges are moved apart: Increase
What is electric potential difference?
• The change in PE per unit charge.– How can it be calculated?
What is a volt?
• Unit for electric potential energy (potential difference.)
• Joules of energy required to move 1c between two points in an electric field.
• Measured with a voltmeter
What is a volt?
Ex) 27J of work are required to move a charge of 3c, What is the voltage?
What is an electron-volt?
• Another unit for work
• The energy required to move 1 electron (or proton) through a potential difference of 1 volt.
1ev = 1.60x10-19J (in reference table)
Electron Volt
• Ex) What quantity is equivalent to 4.8x10-17 joules?
a) 4.8 ev
b) 4.8x10-17 ev
c) 300 ev
d) 480 ev
Electric Potential difference in a Uniform Field
The electric field intensity between two large, charged, parallel metal plates is 6000 N/c. The
plates are 0.05 m apart.
• What is the electric potential difference between them?
• The electric field intensity between two parallel plates is 4.0x104 N/c. If the plates are separated by 5.0x10-3 m, what is the potential difference of the plates?
a) 3.0x104 volts
b) 200 volts
c) 8.0x106 volts
d) 120 volts
Example
Which has the greater Electric Potential Difference
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Which has the greater Electric Potential Difference
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