Ions in Salt Solution
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 -
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Exercise:
When a current flows through a salt solution the positive and negative ions drift in opposite directions. Show that the force on the ions has the direction predicted using the right-hand rule for the direction of the conventional current.
Solution:
The positive ions on average move in the direction defined by the macroscopic current whereas the negative ions move in the opposite direction. Since they have unlike charges and opposite directions the force vectors acting on them po in the same direction see examples in figure below. center includegraphicswidthtextwidth#image_path:salt-solution# center In reality the motion of the ions is a complicated sequence of accelerations in the electric field and collision with other particles in the liquid. There are always ions moving in the "wrong" direction for a short while after a collision but on average the majority of particles drift in the direction described above.
When a current flows through a salt solution the positive and negative ions drift in opposite directions. Show that the force on the ions has the direction predicted using the right-hand rule for the direction of the conventional current.
Solution:
The positive ions on average move in the direction defined by the macroscopic current whereas the negative ions move in the opposite direction. Since they have unlike charges and opposite directions the force vectors acting on them po in the same direction see examples in figure below. center includegraphicswidthtextwidth#image_path:salt-solution# center In reality the motion of the ions is a complicated sequence of accelerations in the electric field and collision with other particles in the liquid. There are always ions moving in the "wrong" direction for a short while after a collision but on average the majority of particles drift in the direction described above.
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Exercise:
When a current flows through a salt solution the positive and negative ions drift in opposite directions. Show that the force on the ions has the direction predicted using the right-hand rule for the direction of the conventional current.
Solution:
The positive ions on average move in the direction defined by the macroscopic current whereas the negative ions move in the opposite direction. Since they have unlike charges and opposite directions the force vectors acting on them po in the same direction see examples in figure below. center includegraphicswidthtextwidth#image_path:salt-solution# center In reality the motion of the ions is a complicated sequence of accelerations in the electric field and collision with other particles in the liquid. There are always ions moving in the "wrong" direction for a short while after a collision but on average the majority of particles drift in the direction described above.
When a current flows through a salt solution the positive and negative ions drift in opposite directions. Show that the force on the ions has the direction predicted using the right-hand rule for the direction of the conventional current.
Solution:
The positive ions on average move in the direction defined by the macroscopic current whereas the negative ions move in the opposite direction. Since they have unlike charges and opposite directions the force vectors acting on them po in the same direction see examples in figure below. center includegraphicswidthtextwidth#image_path:salt-solution# center In reality the motion of the ions is a complicated sequence of accelerations in the electric field and collision with other particles in the liquid. There are always ions moving in the "wrong" direction for a short while after a collision but on average the majority of particles drift in the direction described above.
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