Currents and Voltages in a Circuit
About points...
We associate a certain number of points with each exercise.
When you click an exercise into a collection, this number will be taken as points for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit the number of points for the exercise in the collection independently, without any effect on "points by default" as represented by the number here.
That being said... How many "default points" should you associate with an exercise upon creation?
As with difficulty, there is no straight forward and generally accepted way.
But as a guideline, we tend to give as many points by default as there are mathematical steps to do in the exercise.
Again, very vague... But the number should kind of represent the "work" required.
When you click an exercise into a collection, this number will be taken as points for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit the number of points for the exercise in the collection independently, without any effect on "points by default" as represented by the number here.
That being said... How many "default points" should you associate with an exercise upon creation?
As with difficulty, there is no straight forward and generally accepted way.
But as a guideline, we tend to give as many points by default as there are mathematical steps to do in the exercise.
Again, very vague... But the number should kind of represent the "work" required.
About difficulty...
We associate a certain difficulty with each exercise.
When you click an exercise into a collection, this number will be taken as difficulty for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit its difficulty in the collection independently, without any effect on the "difficulty by default" here.
Why we use chess pieces? Well... we like chess, we like playing around with \(\LaTeX\)-fonts, we wanted symbols that need less space than six stars in a table-column... But in your layouts, you are of course free to indicate the difficulty of the exercise the way you want.
That being said... How "difficult" is an exercise? It depends on many factors, like what was being taught etc.
In physics exercises, we try to follow this pattern:
Level 1 - One formula (one you would find in a reference book) is enough to solve the exercise. Example exercise
Level 2 - Two formulas are needed, it's possible to compute an "in-between" solution, i.e. no algebraic equation needed. Example exercise
Level 3 - "Chain-computations" like on level 2, but 3+ calculations. Still, no equations, i.e. you are not forced to solve it in an algebraic manner. Example exercise
Level 4 - Exercise needs to be solved by algebraic equations, not possible to calculate numerical "in-between" results. Example exercise
Level 5 -
Level 6 -
When you click an exercise into a collection, this number will be taken as difficulty for the exercise, kind of "by default".
But once the exercise is on the collection, you can edit its difficulty in the collection independently, without any effect on the "difficulty by default" here.
Why we use chess pieces? Well... we like chess, we like playing around with \(\LaTeX\)-fonts, we wanted symbols that need less space than six stars in a table-column... But in your layouts, you are of course free to indicate the difficulty of the exercise the way you want.
That being said... How "difficult" is an exercise? It depends on many factors, like what was being taught etc.
In physics exercises, we try to follow this pattern:
Level 1 - One formula (one you would find in a reference book) is enough to solve the exercise. Example exercise
Level 2 - Two formulas are needed, it's possible to compute an "in-between" solution, i.e. no algebraic equation needed. Example exercise
Level 3 - "Chain-computations" like on level 2, but 3+ calculations. Still, no equations, i.e. you are not forced to solve it in an algebraic manner. Example exercise
Level 4 - Exercise needs to be solved by algebraic equations, not possible to calculate numerical "in-between" results. Example exercise
Level 5 -
Level 6 -
Question
Solution
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Exercise:
Determine the missing currents I_ I_ and I_ the potentials at the labelled pos B C and E and the voltages across the three light bulbs in the circuit below. center includegraphicswidth.mm#image_path:currents-voltages-# center
Solution:
The current before and after a light bulb has to be the same so I_Ib. With Kirchhoff's junction rule for junction B we find that I_ I - Ib IaP For the current I_ we can either add the two currents entering junction D or use the fact that the total current leaving the battery has to be the same as the current returning to the battery i.e. I_ I. vspacemm For an ideal wire the potential at B is the same as the potential at A: V_BVA. The potential at C is DVxO lower than at B so V_C VCP. The potential at E is DVO lower than at A so V_E VEP. vspacemm The voltages across the light bulbs can be calculated as the differences between the potentials before and after the light bulbs: Delta V_ DVaF VCP-VD DVaP Delta V_ DVbF VBP-VD DVbP Delta V_ DVcF VD-VEP DVcP
Determine the missing currents I_ I_ and I_ the potentials at the labelled pos B C and E and the voltages across the three light bulbs in the circuit below. center includegraphicswidth.mm#image_path:currents-voltages-# center
Solution:
The current before and after a light bulb has to be the same so I_Ib. With Kirchhoff's junction rule for junction B we find that I_ I - Ib IaP For the current I_ we can either add the two currents entering junction D or use the fact that the total current leaving the battery has to be the same as the current returning to the battery i.e. I_ I. vspacemm For an ideal wire the potential at B is the same as the potential at A: V_BVA. The potential at C is DVxO lower than at B so V_C VCP. The potential at E is DVO lower than at A so V_E VEP. vspacemm The voltages across the light bulbs can be calculated as the differences between the potentials before and after the light bulbs: Delta V_ DVaF VCP-VD DVaP Delta V_ DVbF VBP-VD DVbP Delta V_ DVcF VD-VEP DVcP
Meta Information
Exercise:
Determine the missing currents I_ I_ and I_ the potentials at the labelled pos B C and E and the voltages across the three light bulbs in the circuit below. center includegraphicswidth.mm#image_path:currents-voltages-# center
Solution:
The current before and after a light bulb has to be the same so I_Ib. With Kirchhoff's junction rule for junction B we find that I_ I - Ib IaP For the current I_ we can either add the two currents entering junction D or use the fact that the total current leaving the battery has to be the same as the current returning to the battery i.e. I_ I. vspacemm For an ideal wire the potential at B is the same as the potential at A: V_BVA. The potential at C is DVxO lower than at B so V_C VCP. The potential at E is DVO lower than at A so V_E VEP. vspacemm The voltages across the light bulbs can be calculated as the differences between the potentials before and after the light bulbs: Delta V_ DVaF VCP-VD DVaP Delta V_ DVbF VBP-VD DVbP Delta V_ DVcF VD-VEP DVcP
Determine the missing currents I_ I_ and I_ the potentials at the labelled pos B C and E and the voltages across the three light bulbs in the circuit below. center includegraphicswidth.mm#image_path:currents-voltages-# center
Solution:
The current before and after a light bulb has to be the same so I_Ib. With Kirchhoff's junction rule for junction B we find that I_ I - Ib IaP For the current I_ we can either add the two currents entering junction D or use the fact that the total current leaving the battery has to be the same as the current returning to the battery i.e. I_ I. vspacemm For an ideal wire the potential at B is the same as the potential at A: V_BVA. The potential at C is DVxO lower than at B so V_C VCP. The potential at E is DVO lower than at A so V_E VEP. vspacemm The voltages across the light bulbs can be calculated as the differences between the potentials before and after the light bulbs: Delta V_ DVaF VCP-VD DVaP Delta V_ DVbF VBP-VD DVbP Delta V_ DVcF VD-VEP DVcP
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