Energy and Electrostatics. A new definition of potential energy An object has potential energy due...
-
Upload
rhoda-anthony -
Category
Documents
-
view
212 -
download
0
Transcript of Energy and Electrostatics. A new definition of potential energy An object has potential energy due...
![Page 1: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/1.jpg)
Energy and Electrostatics
![Page 2: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/2.jpg)
A new definition of potential energy
• An object has potential energy due to its location within a force field.
• To change the object’s location (and therefore potential energy), work has to be done by applying a force on the object.
![Page 3: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/3.jpg)
Mechanical example• Work is done to lift an object against the
gravitational force field of Earth. (unnatural movement)
• When released, the potential energy is converted into kinetic energy, and the object moves in the direction of the force field naturally.
![Page 4: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/4.jpg)
Electric potential energy
• A charged object has PE due to its location within an electric field.
• Work is required to move a charged object against the electric field. When released, that PE will be converted into KE naturally in the direction of the field.
![Page 5: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/5.jpg)
Guiding questions
• Answer questions #1 - #5 now please.
![Page 6: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/6.jpg)
Electric Potential
• In electricity, rather than deal with total PE, it is more convenient to deal with electric potential energy per charge since there could be many charges in the field (think a circuit)
• We call this electric potential for short– Measured in Volts, and symbolized with a “V”
fieldinech
energypotentialelectricV
__arg
__
![Page 7: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/7.jpg)
Electric potential
• Rearranging the previous equation, we get…• W = qV• When we get to circuits, this will be useful
because if we are using a 9V battery, the amount of work we get out of a charge moving through the circuit will be 9V*charge.
![Page 8: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/8.jpg)
More about Volts
• 1 volt = 1 joule of energy per coulomb of charge
• Example, if a conductor has a potential of 1000 volts, it would take 1000 joules of energy per coulomb to bring a small charge from far away and add it to the charge of the conductor.
![Page 9: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/9.jpg)
Guiding questions
• Answer #6 now please
![Page 10: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/10.jpg)
CurrentCurrentThe movement of electrons
through a conductor. The rate at which charge flows.
time
chargecurrent
DC (Direct Current) – All charges move in one direction in the circuit.
AC (Alternating Current) – charges move one way and then the other, changing direction from moment to moment.
I =q
t
units: CoulombsSecond
= Ampere = Amp = A
![Page 11: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/11.jpg)
CIRCUITCIRCUIT:
A path where electrons flow and
their energy is used.RESISTANCERESISTANCE:
Opposition to the flow of electrons in a
circuit.
![Page 12: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/12.jpg)
THE DAM ANALOGYDam = Battery, Outlet, Power Supply
Water Depth =
V = Voltage or Potential
Valve = Resistance or Current Control
Water Wheel = Energy
User/Converter (Light Bulb, Motor…)Pipe =
Wire
Current
GROUND or Lowest Potential
![Page 13: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/13.jpg)
How can the resistance change?
• What are the variables that effect the resistance of the flow of the water in the Dam Analogy?
• Resistance is much like friction. The more “friction” against a current, the more resistance.
![Page 14: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/14.jpg)
First variable
• What would happen if we widen the path for the water?
• The resistance would be less.
• Therefore: R is in proportion to 1/A
![Page 15: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/15.jpg)
2nd variable
• What would happen if we shorten the path of the valve?
• There would be less to flow through, therefore the resistance would be less.
• Therefore, R is proportional to L
![Page 16: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/16.jpg)
3rd variable
• What would happen if we thicken the walls of the pathway for the water?
• There would be more resistance.
• Therefore, R is proportional to density of the material.
![Page 17: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/17.jpg)
4th variable
• What would happen if we heat up the pathway of the water?
• The resistance would increase
• As resistance goes up, temperature goes up.
![Page 18: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/18.jpg)
Summary
• Resistance of an object depends on1) Cross-sectional area of the resistor2) Length of the resistor3) Density of the resistor4) Temperature of the resistor
![Page 19: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/19.jpg)
Guiding questions
• Answer #7 now please
![Page 20: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/20.jpg)
What does the dam analogy What does the dam analogy tell us about the relationship tell us about the relationship
between I and R?between I and R?As R increases, I ……As R increases, I ……
DECREASES!DECREASES!oror
![Page 21: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/21.jpg)
How could the current be How could the current be increased in a circuit whose increased in a circuit whose resistance is held constant?resistance is held constant?Increase the “push” or Increase the “push” or
VOLTAGEVOLTAGE
![Page 22: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/22.jpg)
Georg Simon Ohm
Ohm’s Law:
R
V I
Resistance
Voltage Current OR
IR V I
V R
More Typically Written As:Can Be Written As:
UNITS FOR UNITS FOR RESISTANCERESISTANCE
Amp
VoltsOhm
This tells you the number of volts necessary to push 1 amp of current through the device.
![Page 23: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/23.jpg)
Power
• Deriving power of a circuit• P = Work/time• How is work related to potential of a circuit?
![Page 24: Energy and Electrostatics. A new definition of potential energy An object has potential energy due to its location within a force field. To change the.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1d5503460f94c339b5/html5/thumbnails/24.jpg)
Guiding questions
• Answer #8 now please.