Lesson 4: Electric Fields
Overview:
In this activity, you will explore electric fields. You will learn about electric field lines and electric field intensity. You will learn how to solve quantitative problems with this new concept and then compare electric fields and forces to gravitational fields and forces.
Curriculum Expectations:
Overall Expectations:
D2. Investigate, in qualitative and quantitative terms, gravitational, electric, and magnetic fields, and solve related problems.
D3. Demonstrate an understanding of the concepts, properties, principles, and laws related to gravitational, electric, and magnetic fields and their interactions with matter.
Specific Expectations:
D2.1 Use appropriate terminology related to fields, including, but not limited to: forces, potential energies, potential, and exchange particles.
D2.3 Analyze, and solve problems involving, electric force, field strength, potential energy, and potential as they apply to uniform and non-uniform electric fields (e.g., the fields produced by a parallel plate and by point charges).
D2.5 Conduct a laboratory inquiry or computer simulation to examine the behaviour of a particle in a field (e.g., test Coulomb’s law; replicate Millikan’s experiment or Rutherford’s scattering experiment; use a bubble or cloud chamber).
D3.2 Compare and contrast the corresponding properties of gravitational, electric, and magnetic fields (e.g., the strength of each field; the relationship between charge in electric fields and mass in gravitational fields).
D3.3 Use field diagrams to explain differences in the sources and directions of fields, including, but not limited to, differences between near- Earth and distant fields, parallel plates and point charges, straight line conductors and solenoids.
D2. Investigate, in qualitative and quantitative terms, gravitational, electric, and magnetic fields, and solve related problems.
D3. Demonstrate an understanding of the concepts, properties, principles, and laws related to gravitational, electric, and magnetic fields and their interactions with matter.
Specific Expectations:
D2.1 Use appropriate terminology related to fields, including, but not limited to: forces, potential energies, potential, and exchange particles.
D2.3 Analyze, and solve problems involving, electric force, field strength, potential energy, and potential as they apply to uniform and non-uniform electric fields (e.g., the fields produced by a parallel plate and by point charges).
D2.5 Conduct a laboratory inquiry or computer simulation to examine the behaviour of a particle in a field (e.g., test Coulomb’s law; replicate Millikan’s experiment or Rutherford’s scattering experiment; use a bubble or cloud chamber).
D3.2 Compare and contrast the corresponding properties of gravitational, electric, and magnetic fields (e.g., the strength of each field; the relationship between charge in electric fields and mass in gravitational fields).
D3.3 Use field diagrams to explain differences in the sources and directions of fields, including, but not limited to, differences between near- Earth and distant fields, parallel plates and point charges, straight line conductors and solenoids.
Success Criteria:
- Describe the properties of the electric field.
- How do you measure the electric force inside a constant electric field?
- How can you determine the direction of the electric force inside a constant electric field?
- By convention, what type of charge is used to determine the direction of the electric field?
- Derive the equation to calculate the magnitude of the electric field.
- What are electric field lines? What are the three things to consider when drawing electric field lines for point charges?
- How do two point charges that interact through Coulomb's law "know" about each other?
- What is the relationship between the net electric field and electric field lines?
- Describe the properties of the electric field between two oppositely charged plates, such as those found in dry battery cells.
Time Allocation: 3 hours
Learning Activities:
Read pages 334 - 344 from Nelson 7.3
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Electric Field of Dreams
Play ball! Add charges to the Field of Dreams and see how they react to the electric field. Turn on a background electric field and adjust the direction and magnitude. (Kevin Costner not included). |
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Electric field of a charged sphere.
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Electric field lines near a positive and a negative point charge.
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In the playlist below, video:
- The electric field, charges, forces, accelerating particles, there's so much to cover and it's all so much fun! In this four part lecture series I'll introduce you to the principles used to accelerate atoms to 99.9% the speed of light in the LHC.
- Will find the electric field of the electric dipole.
Practice questions 2 and 3 on page 337.
Task:
Solve questions 2 and 3 from Nelson 7.3 Review on page 345.
Optional Extension:
Optional Extension:
- Solve questions 4, 6, and 7 on page 345.
Reflect:
Is a flame really a plasma? Well it depends on your definition of plasma, but there are certainly ions in a flame, formed as molecules collide with each other at high speed, sometimes knocking electrons off of their atoms.
Special thanks to the Palais de la Decouverte for helping me perform this experiment. Using tens of thousands of volts on two metal plates, we created a strong electric field around the plasma. This pulled positive ions in one direction and negative ions in the other direction elongating the flame horizontally and causing it to flicker like a "papillon" (butterfly). Then we showed that much longer sparks can be made through the flame than through air since the ions increase the conductivity.
Special thanks to the Palais de la Decouverte for helping me perform this experiment. Using tens of thousands of volts on two metal plates, we created a strong electric field around the plasma. This pulled positive ions in one direction and negative ions in the other direction elongating the flame horizontally and causing it to flicker like a "papillon" (butterfly). Then we showed that much longer sparks can be made through the flame than through air since the ions increase the conductivity.
Additional Resources:
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In this video it will find the electric field of an infinite line charge.
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In this video it will find the electric field of a ring of charge.
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