Unit Planner: Electric fields and charge
Unit 9: Electric field and current
Text book reference
Hamper SL 185 - 196
Inquiry: Establishing the purpose of the unit
List here one to three big, overarching, long-term goals for this unit. Transfer goals are the major goals that ask students to “transfer”, or apply, their knowledge, skills, and concepts at the end of the unit under new/different circumstances, and on their own without scaffolding from the teacher.
- Use of fields to model a force that acts over distance.
- Positive charge flows from high potential to low potential
List here the key content that students will know by the end of the unit
- Observe that, when rubbed, some materials experience a force that acts without the bodies touching and that this force can be attractive or repulsive depending on what materials are used.
- Define field strength as force per unit charge.
Note: Electric field lines aren't actually mentioned in the subject guide but I see no reason to leave them out.
- See the similarity between gravitational and electric fields.
- Define electrical potential.
- Derive I = nAve
- Accept that conventional current is opposite to electron flow.
- Use the model to explain the difference between conductors, insulators, semi conductors and super conductors.
List here the key skills that students will develop by the end of the unit.
- Use Coulombs law to calculate the force between two point charges.
- Draw field lines for radial and uniform fields.
- Add the field strengths due to two or more bodies.
List here the key concepts that students will understand by the end of the unit
- Understand how we can explain this force in terms of positive and negative charge.
- Understand that a the PE of a charge in an E field is dependent on its position.
- Understand the field strength is a vector but potential is a scalar.
- Understand that field strength is equal to potential gradient.
- Understand how the particle model of matter leads to an explanation of resistance and its relation to temperature.
Examples of real world practical applications of knowledge.
Action: teaching and learning through Inquiry
Approaches to teaching
Tick boxes to indicate pedagogical approaches used.
xSmall group work (pairs)
xHands on practical
Examples of how TOK can be introduced in this unit
- Isn't it convenient that matter is made of + and - charge that add and cancel just like numbers. If there had been a 3rd type * and you had to have a +, - and a * to produce a neutral body then we couldn't use numbers to represent them. Is our number system the same as the charges by chance or is there something more deep rooted? Did we come up with the model of charge because our number system works like that or does our number system work like it does because our brains are made of two charges?
- The similarity between our model of electric and gravitational fields is worth mentioning.
- Could there be two masses in the same way as there are two charges?
- Why was field defined in terms of +ve charge?
- Electric and gravitational forces are very similar, why is the universe so symmetric?
- If there existed "negative mass" it would fit nicely into our field model. Does this mean it exists?
- Current flows downhill but electrons flow uphill. Imagining charges flowing uphill does not help us to understand this concept. Are realities sometimes changed to fit our analogies?
- Is the fairy model of the battery (as in Electrical Conduction) an acceptable theory?
Examples of how NOS can be introduced in this unit.
- The way rubbed objects interact with each other can not be explained using the mechanics covered in the course so far. A new theory has to be developed and before doing that a new property (charge) has to be assigned.
- Field lines are a useful visual representation of a field.
- Models are developed to explain phenomena that we can't see directly.
worksheets and exercises
What went well
List the portions of the unit (content, assessment, planning) that were successful
What didn’t work well
List the portions of the unit (content, assessment, planning) that were not as successful as hoped
List any notes, suggestions, or considerations for the future teaching of this unit