Crossed Fields
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:
In the classroom demonstration for crossed fields electrons travel through an electric field with strength EO and a magnetic field with strength BO. The fields are perpicular to each other and to the trajectory of the electrons. Electrons with an acceleration voltage of VO follow an approximately straight trajectory. abcliste abc Based on the strengths of the electric and magnetic field what is the expected velocity of electrons following a straight path? abc Calculate the velocity of the electrons in the demonstration. What are possible reasons for the deviation from the predicted value? abcliste
Solution:
abcliste abc Electrons are not deflected if the condition for the force equilibrium in the crossed fields is fulfilled: v_ vaF fracEB va resultvacP abc The acceleration voltage leads to an increase in kinetic energy: e Delta V frac m v^ It follows for the velocity of the accelerated electrons v vbF sqrtfractimes nce times Vncme vb resultvbcP This is considerably faster than the predicted value. The main reason is that the magnetic field in the demonstration experiment is not really uniform and also exts beyond the electric field i.e. electrons travel through the magnetic field before and after the region where they experience both the electric and magnetic force. abcliste
In the classroom demonstration for crossed fields electrons travel through an electric field with strength EO and a magnetic field with strength BO. The fields are perpicular to each other and to the trajectory of the electrons. Electrons with an acceleration voltage of VO follow an approximately straight trajectory. abcliste abc Based on the strengths of the electric and magnetic field what is the expected velocity of electrons following a straight path? abc Calculate the velocity of the electrons in the demonstration. What are possible reasons for the deviation from the predicted value? abcliste
Solution:
abcliste abc Electrons are not deflected if the condition for the force equilibrium in the crossed fields is fulfilled: v_ vaF fracEB va resultvacP abc The acceleration voltage leads to an increase in kinetic energy: e Delta V frac m v^ It follows for the velocity of the accelerated electrons v vbF sqrtfractimes nce times Vncme vb resultvbcP This is considerably faster than the predicted value. The main reason is that the magnetic field in the demonstration experiment is not really uniform and also exts beyond the electric field i.e. electrons travel through the magnetic field before and after the region where they experience both the electric and magnetic force. abcliste
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Exercise:
In the classroom demonstration for crossed fields electrons travel through an electric field with strength EO and a magnetic field with strength BO. The fields are perpicular to each other and to the trajectory of the electrons. Electrons with an acceleration voltage of VO follow an approximately straight trajectory. abcliste abc Based on the strengths of the electric and magnetic field what is the expected velocity of electrons following a straight path? abc Calculate the velocity of the electrons in the demonstration. What are possible reasons for the deviation from the predicted value? abcliste
Solution:
abcliste abc Electrons are not deflected if the condition for the force equilibrium in the crossed fields is fulfilled: v_ vaF fracEB va resultvacP abc The acceleration voltage leads to an increase in kinetic energy: e Delta V frac m v^ It follows for the velocity of the accelerated electrons v vbF sqrtfractimes nce times Vncme vb resultvbcP This is considerably faster than the predicted value. The main reason is that the magnetic field in the demonstration experiment is not really uniform and also exts beyond the electric field i.e. electrons travel through the magnetic field before and after the region where they experience both the electric and magnetic force. abcliste
In the classroom demonstration for crossed fields electrons travel through an electric field with strength EO and a magnetic field with strength BO. The fields are perpicular to each other and to the trajectory of the electrons. Electrons with an acceleration voltage of VO follow an approximately straight trajectory. abcliste abc Based on the strengths of the electric and magnetic field what is the expected velocity of electrons following a straight path? abc Calculate the velocity of the electrons in the demonstration. What are possible reasons for the deviation from the predicted value? abcliste
Solution:
abcliste abc Electrons are not deflected if the condition for the force equilibrium in the crossed fields is fulfilled: v_ vaF fracEB va resultvacP abc The acceleration voltage leads to an increase in kinetic energy: e Delta V frac m v^ It follows for the velocity of the accelerated electrons v vbF sqrtfractimes nce times Vncme vb resultvbcP This is considerably faster than the predicted value. The main reason is that the magnetic field in the demonstration experiment is not really uniform and also exts beyond the electric field i.e. electrons travel through the magnetic field before and after the region where they experience both the electric and magnetic force. abcliste
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