Old and New Battery
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:
A new battery VnO rnO and an old battery VoO roO are connected in parallel. Calculate the current flowing through this circuit without an external load.
Solution:
The figure shows the equivalent circuit for the two batteries with their ernal resistances. center includegraphics#image_path:old-new-battery-# center For the loop defined by the connected batteries the polarities of the batteries have opposite directions i.e. the total voltage corresponds to the difference of the two source voltages: sscDelta Vtot sscDelta Vnew - sscDelta Vold The total resistance is sscrtot sscrnew + sscrold It follows for the current I fracsscDelta Vtotsscrtot IF fracVn - Vorn + ro I approx resultIP- This is not a large current but in a lot of battery-powered devices the batteries remain connected even if the external load is switched off so the current is always flowing. This is the reason you should never mix fresh and old batteries.
A new battery VnO rnO and an old battery VoO roO are connected in parallel. Calculate the current flowing through this circuit without an external load.
Solution:
The figure shows the equivalent circuit for the two batteries with their ernal resistances. center includegraphics#image_path:old-new-battery-# center For the loop defined by the connected batteries the polarities of the batteries have opposite directions i.e. the total voltage corresponds to the difference of the two source voltages: sscDelta Vtot sscDelta Vnew - sscDelta Vold The total resistance is sscrtot sscrnew + sscrold It follows for the current I fracsscDelta Vtotsscrtot IF fracVn - Vorn + ro I approx resultIP- This is not a large current but in a lot of battery-powered devices the batteries remain connected even if the external load is switched off so the current is always flowing. This is the reason you should never mix fresh and old batteries.
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Exercise:
A new battery VnO rnO and an old battery VoO roO are connected in parallel. Calculate the current flowing through this circuit without an external load.
Solution:
The figure shows the equivalent circuit for the two batteries with their ernal resistances. center includegraphics#image_path:old-new-battery-# center For the loop defined by the connected batteries the polarities of the batteries have opposite directions i.e. the total voltage corresponds to the difference of the two source voltages: sscDelta Vtot sscDelta Vnew - sscDelta Vold The total resistance is sscrtot sscrnew + sscrold It follows for the current I fracsscDelta Vtotsscrtot IF fracVn - Vorn + ro I approx resultIP- This is not a large current but in a lot of battery-powered devices the batteries remain connected even if the external load is switched off so the current is always flowing. This is the reason you should never mix fresh and old batteries.
A new battery VnO rnO and an old battery VoO roO are connected in parallel. Calculate the current flowing through this circuit without an external load.
Solution:
The figure shows the equivalent circuit for the two batteries with their ernal resistances. center includegraphics#image_path:old-new-battery-# center For the loop defined by the connected batteries the polarities of the batteries have opposite directions i.e. the total voltage corresponds to the difference of the two source voltages: sscDelta Vtot sscDelta Vnew - sscDelta Vold The total resistance is sscrtot sscrnew + sscrold It follows for the current I fracsscDelta Vtotsscrtot IF fracVn - Vorn + ro I approx resultIP- This is not a large current but in a lot of battery-powered devices the batteries remain connected even if the external load is switched off so the current is always flowing. This is the reason you should never mix fresh and old batteries.
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