7.3.4
Electric Potential
Electric Potential
Electric Potential
Electric potential is the work done to move a positive test charge from infinity to a given point within the field.
![Illustrative background for Work done](https://image-v2.cdn.app.senecalearning.com/2018-09/89c1e0f1-8dbd-4aa1-99a1-6c1144bd51e2/infinity-8-eight-,h_400,q_80,w_640.jpg)
![Illustrative background for Work done ?? "content](https://image-v2.cdn.app.senecalearning.com/2018-09/89c1e0f1-8dbd-4aa1-99a1-6c1144bd51e2/infinity-8-eight-,h_400,q_80,w_640.jpg)
Work done
Work done
- Electric potential is the work which you need to do to bring a positive point charge to a distance, r, from the charge making the field.
- The potential at infinity is zero.
- The potential is largest right next to the charge.
![Illustrative background for Calculating the potential](https://image-v2.cdn.app.senecalearning.com/2018-08/f732fabc-e043-41bc-a097-cdbeee0213b9/man-thinking-memory,h_400,q_80,w_640.jpg)
![Illustrative background for Calculating the potential ?? "content](https://image-v2.cdn.app.senecalearning.com/2018-08/f732fabc-e043-41bc-a097-cdbeee0213b9/man-thinking-memory,h_400,q_80,w_640.jpg)
Calculating the potential
Calculating the potential
- Electric potential = constant x charge ÷ distance
- Potential is proportional to so falls off more slowly than force or field
Moving in an Electric Field
Moving in an Electric Field
In order to move a charge through a field, work must be done as the energy of the charge will change.
![Illustrative background for Equipotentials](https://image-v2.cdn.app.senecalearning.com/courseImages/physics/4.2.1 Electric Charge/electricity-min,h_400,q_80,w_640.jpg)
![Illustrative background for Equipotentials ?? "content](https://image-v2.cdn.app.senecalearning.com/courseImages/physics/4.2.1 Electric Charge/electricity-min,h_400,q_80,w_640.jpg)
Equipotentials
Equipotentials
- An equipotential line or surface is one on which the voltage is constant.
- This means that there is no change in potential difference or energy if a charge just moves along this line or surface.
- No work is done if a charge moves along an equipotential.
- Equipotential lines are placed at equal intervals of energy
![Illustrative background for Point charge equipotential](https://image-v2.cdn.app.senecalearning.com/2018-09/c4277316-2115-4aa6-bf71-502ba9896468/point-charge-equipotential,h_400,q_80,w_640.png)
![Illustrative background for Point charge equipotential ?? "content](https://image-v2.cdn.app.senecalearning.com/2018-09/c4277316-2115-4aa6-bf71-502ba9896468/point-charge-equipotential,h_400,q_80,w_640.png)
Point charge equipotential
Point charge equipotential
- For a charge equipotential lines are circles of constant radius.
- As the lines get further from the charge the gaps between the lines get larger .
![Illustrative background for Parallel plate equipotential](https://image-v2.cdn.app.senecalearning.com/2018-09/f06bc625-b904-4215-96be-87c0b2c0ee36/parallel-plate-equipotential,h_400,q_80,w_640.png)
![Illustrative background for Parallel plate equipotential ?? "content](https://image-v2.cdn.app.senecalearning.com/2018-09/f06bc625-b904-4215-96be-87c0b2c0ee36/parallel-plate-equipotential,h_400,q_80,w_640.png)
Parallel plate equipotential
Parallel plate equipotential
- For parallel plates, equipotential lines are straight lines parallel to the plates.
- These straight lines are evenly spaced as the field is uniform.
![Illustrative background for Work done](https://image-v2.cdn.app.senecalearning.com/courseImages/physics/4.2.1 Electric Charge/electric-field-min,h_400,q_80,w_640.jpg)
![Illustrative background for Work done ?? "content](https://image-v2.cdn.app.senecalearning.com/courseImages/physics/4.2.1 Electric Charge/electric-field-min,h_400,q_80,w_640.jpg)
Work done
Work done
- Work done to move a charge = charge x change in potential difference
- If the charge is moved between equipotential lines then work is done.
- can be found by finding the area under a field-distance graph.
Electric Potential Graph
Electric Potential Graph
Gravitational potentials and electrostatic potentials have very similar graphs.
![Illustrative background for Comparison to gravitational potential](https://image-v2.cdn.app.senecalearning.com/2018-08/99374102-4afb-49c6-a269-0c66ef60d0c4/mercury-822825_1280,h_400,q_80,w_640.png)
![Illustrative background for Comparison to gravitational potential ?? "content](https://image-v2.cdn.app.senecalearning.com/2018-08/99374102-4afb-49c6-a269-0c66ef60d0c4/mercury-822825_1280,h_400,q_80,w_640.png)
Comparison to gravitational potential
Comparison to gravitational potential
- The gravitational field strength around a point mass and the electrostatic field around a point charge have the same patterns, although they are different magnitudes.
- The formulae for the relationship between the field strength and distance both include inverse-squares.
- The significant difference is that electrostatic fields can have either positive or negative values, indicating that the force can either be repulsive or attractive respectively.
![Illustrative background for Calculating work done](https://image-v2.cdn.app.senecalearning.com/courseImages/physics/AQA New Modules/8.1.1/black dwarf,h_400,q_80,w_640.jpg)
![Illustrative background for Calculating work done ?? "content](https://image-v2.cdn.app.senecalearning.com/courseImages/physics/AQA New Modules/8.1.1/black dwarf,h_400,q_80,w_640.jpg)
Calculating work done
Calculating work done
- Just like in the gravitational case, the work done in moving a positive charge away from a central positive charge can be calculated by finding the area underneath the appropriate curve.
![Illustrative background for Positive or negative charge](https://image-v2.cdn.app.senecalearning.com/2018-07/8ad13556-c0ec-441d-ac9d-f81024e26da2/Positive-Negative-Up-Down-Yes-No-,h_400,q_80,w_640.jpg)
![Illustrative background for Positive or negative charge ?? "content](https://image-v2.cdn.app.senecalearning.com/2018-07/8ad13556-c0ec-441d-ac9d-f81024e26da2/Positive-Negative-Up-Down-Yes-No-,h_400,q_80,w_640.jpg)
Positive or negative charge
Positive or negative charge
- The electrostatic potential-distance graphs mirror those of the gravitational potential-distance graphs.
![Illustrative background for Positive or negative charge 2](https://image-v2.cdn.app.senecalearning.com/courseImages/chemistry/9.1.2 Carbon dioxide and methane as greenhouse gases/johannes-plenio-356764-min,h_400,q_80,w_640.jpg)
![Illustrative background for Positive or negative charge 2 ?? "content](https://image-v2.cdn.app.senecalearning.com/courseImages/chemistry/9.1.2 Carbon dioxide and methane as greenhouse gases/johannes-plenio-356764-min,h_400,q_80,w_640.jpg)
Positive or negative charge 2
Positive or negative charge 2
- In both cases, the magnitude of the electrostatic potential is given by:
1Measurements & Errors
2Particles & Radiation
2.1Particles
2.1.1Atomic Model
2.1.2Specific Charge, Protons & Neutron Numbers
2.1.3End of Topic Test - Atomic Model
2.1.4Isotopes
2.1.5Stable & Unstable Nuclei
2.1.6End of Topic Test - Isotopes & Nuclei
2.1.7A-A* (AO3/4) - Stable & Unstable Nuclei
2.1.8Particles, Antiparticles & Photons
2.1.9Particle Interactions
2.1.10Classification of Particles
2.1.11End of Topic Test - Particles & Interactions
2.1.12Quarks & Antiquarks
2.1.13Application of Conservation Laws
2.1.14End of Topic Test - Leptons & Quarks
2.1.15Exam-Style Question - Radioactive Decay
2.2Electromagnetic Radiation & Quantum Phenomena
3Waves
3.1Progressive & Stationary Waves
3.2Refraction, Diffraction & Interference
4Mechanics & Materials
4.1Force, Energy & Momentum
4.1.1Scalars & Vectors
4.1.2Vector Problems
4.1.3End of Topic Test - Scalars & Vectors
4.1.4Moments
4.1.5Centre of Mass
4.1.6End of Topic Test - Moments & Centre of Mass
4.1.7Motion in a Straight Line
4.1.8Graphs of Motion
4.1.9Bouncing Ball Example
4.1.10End of Topic Test - Motion in a Straight Line
4.1.11Acceleration Due to Gravity
4.1.12Projectile Motion
4.1.13Friction
4.1.14Terminal Speed
4.1.15End of Topic Test - Acceleration Due to Gravity
4.1.16Newton's Laws
4.1.17Momentum
4.1.18Momentum 2
4.1.19End of Topic Test - Newton's Laws & Momentum
4.1.20A-A* (AO3/4) - Newton's Third Law
4.1.21Work & Energy
4.1.22Power & Efficiency
4.1.23Conservation of Energy
4.1.24End of Topic Test - Work, Energy & Power
4.1.25Exam-Style Question - Forces
5Electricity
5.1Current Electricity
5.1.1Basics of Electricity
5.1.2Current-Voltage Characteristics
5.1.3End of Topic Test - Basics of Electricity
5.1.4Resistivity
5.1.5Superconductivity
5.1.6A-A* (AO3/4) - Superconductivity
5.1.7End of Topic Test - Resistivity & Superconductors
5.1.8Circuits
5.1.9Power and Conservation
5.1.10Potential Divider
5.1.11Emf & Internal Resistance
5.1.12End of Topic Test - Power & Potential
5.1.13Exam-Style Question - Resistance
6Further Mechanics & Thermal Physics (A2 only)
6.1Periodic Motion (A2 only)
6.2Thermal Physics (A2 only)
7Fields & Their Consequences (A2 only)
7.1Fields (A2 only)
7.2Gravitational Fields (A2 only)
7.3Electric Fields (A2 only)
7.4Capacitance (A2 only)
7.5Magnetic Fields (A2 only)
7.5.1Magnetic Flux Density
7.5.2End of Topic Test - Capacitance & Flux Density
7.5.3Moving Charges in a Magnetic Field
7.5.4Magnetic Flux & Flux Linkage
7.5.5Electromagnetic Induction
7.5.6Electromagnetic Induction 2
7.5.7Alternating Currents
7.5.8Operation of a Transformer
7.5.9Magnetic Flux Density
7.5.10End of Topic Test - Electromagnetic Induction
8Nuclear Physics (A2 only)
8.1Radioactivity (A2 only)
8.1.1Rutherford Scattering
8.1.2Alpha & Beta Radiation
8.1.3Gamma Radiation
8.1.4Radioactive Decay
8.1.5Half Life
8.1.6End of Topic Test - Radioactivity
8.1.7Nuclear Instability
8.1.8Nuclear Radius
8.1.9Mass & Energy
8.1.10Binding Energy
8.1.11Induced Fission
8.1.12Safety Aspects of Nuclear Reactors
8.1.13End of Topic Test - Nuclear Physics
8.1.14A-A* (AO3/4) - Nuclear Fusion
9Option: Astrophysics (A2 only)
9.1Telescopes (A2 only)
9.2Classification of Stars (A2 only)
9.3Cosmology (A2 only)
10Option: Medical Physics (A2 only)
10.1Physics of the Eye (A2 only)
10.2Physics of the Ear (A2 only)
10.3Biological Measurement (A2 only)
10.4Non-Ionising Imaging (A2 only)
10.5X-Ray Imaging (A2 only)
10.6Radionuclide Imaging & Therapy (A2 only)
11Option: Engineering Physics (A2 only)
11.1Rotational Dynamics (A2 only)
11.2Thermodynamics & Engines (A2 only)
12Option: Turning Points in Physics (A2 only)
12.1Discovery of the Electron (A2 only)
12.2Wave-Particle Duality (A2 only)
Jump to other topics
1Measurements & Errors
2Particles & Radiation
2.1Particles
2.1.1Atomic Model
2.1.2Specific Charge, Protons & Neutron Numbers
2.1.3End of Topic Test - Atomic Model
2.1.4Isotopes
2.1.5Stable & Unstable Nuclei
2.1.6End of Topic Test - Isotopes & Nuclei
2.1.7A-A* (AO3/4) - Stable & Unstable Nuclei
2.1.8Particles, Antiparticles & Photons
2.1.9Particle Interactions
2.1.10Classification of Particles
2.1.11End of Topic Test - Particles & Interactions
2.1.12Quarks & Antiquarks
2.1.13Application of Conservation Laws
2.1.14End of Topic Test - Leptons & Quarks
2.1.15Exam-Style Question - Radioactive Decay
2.2Electromagnetic Radiation & Quantum Phenomena
3Waves
3.1Progressive & Stationary Waves
3.2Refraction, Diffraction & Interference
4Mechanics & Materials
4.1Force, Energy & Momentum
4.1.1Scalars & Vectors
4.1.2Vector Problems
4.1.3End of Topic Test - Scalars & Vectors
4.1.4Moments
4.1.5Centre of Mass
4.1.6End of Topic Test - Moments & Centre of Mass
4.1.7Motion in a Straight Line
4.1.8Graphs of Motion
4.1.9Bouncing Ball Example
4.1.10End of Topic Test - Motion in a Straight Line
4.1.11Acceleration Due to Gravity
4.1.12Projectile Motion
4.1.13Friction
4.1.14Terminal Speed
4.1.15End of Topic Test - Acceleration Due to Gravity
4.1.16Newton's Laws
4.1.17Momentum
4.1.18Momentum 2
4.1.19End of Topic Test - Newton's Laws & Momentum
4.1.20A-A* (AO3/4) - Newton's Third Law
4.1.21Work & Energy
4.1.22Power & Efficiency
4.1.23Conservation of Energy
4.1.24End of Topic Test - Work, Energy & Power
4.1.25Exam-Style Question - Forces
5Electricity
5.1Current Electricity
5.1.1Basics of Electricity
5.1.2Current-Voltage Characteristics
5.1.3End of Topic Test - Basics of Electricity
5.1.4Resistivity
5.1.5Superconductivity
5.1.6A-A* (AO3/4) - Superconductivity
5.1.7End of Topic Test - Resistivity & Superconductors
5.1.8Circuits
5.1.9Power and Conservation
5.1.10Potential Divider
5.1.11Emf & Internal Resistance
5.1.12End of Topic Test - Power & Potential
5.1.13Exam-Style Question - Resistance
6Further Mechanics & Thermal Physics (A2 only)
6.1Periodic Motion (A2 only)
6.2Thermal Physics (A2 only)
7Fields & Their Consequences (A2 only)
7.1Fields (A2 only)
7.2Gravitational Fields (A2 only)
7.3Electric Fields (A2 only)
7.4Capacitance (A2 only)
7.5Magnetic Fields (A2 only)
7.5.1Magnetic Flux Density
7.5.2End of Topic Test - Capacitance & Flux Density
7.5.3Moving Charges in a Magnetic Field
7.5.4Magnetic Flux & Flux Linkage
7.5.5Electromagnetic Induction
7.5.6Electromagnetic Induction 2
7.5.7Alternating Currents
7.5.8Operation of a Transformer
7.5.9Magnetic Flux Density
7.5.10End of Topic Test - Electromagnetic Induction
8Nuclear Physics (A2 only)
8.1Radioactivity (A2 only)
8.1.1Rutherford Scattering
8.1.2Alpha & Beta Radiation
8.1.3Gamma Radiation
8.1.4Radioactive Decay
8.1.5Half Life
8.1.6End of Topic Test - Radioactivity
8.1.7Nuclear Instability
8.1.8Nuclear Radius
8.1.9Mass & Energy
8.1.10Binding Energy
8.1.11Induced Fission
8.1.12Safety Aspects of Nuclear Reactors
8.1.13End of Topic Test - Nuclear Physics
8.1.14A-A* (AO3/4) - Nuclear Fusion
9Option: Astrophysics (A2 only)
9.1Telescopes (A2 only)
9.2Classification of Stars (A2 only)
9.3Cosmology (A2 only)
10Option: Medical Physics (A2 only)
10.1Physics of the Eye (A2 only)
10.2Physics of the Ear (A2 only)
10.3Biological Measurement (A2 only)
10.4Non-Ionising Imaging (A2 only)
10.5X-Ray Imaging (A2 only)
10.6Radionuclide Imaging & Therapy (A2 only)
11Option: Engineering Physics (A2 only)
11.1Rotational Dynamics (A2 only)
11.2Thermodynamics & Engines (A2 only)
12Option: Turning Points in Physics (A2 only)
12.1Discovery of the Electron (A2 only)
12.2Wave-Particle Duality (A2 only)
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