Filament
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
Short
Video
\(\LaTeX\)
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Visit our YouTube-Channel to see solutions to other exercises.
Don't forget to subscribe to our channel, like the videos and leave comments!
Exercise:
A typical incandescent light bulb with a power of PO has a tungsten filament with length LO and diameter dO. abcliste abc When the light bulb is on the electric power is converted to radiation. Calculate the temperature of the filament that allows for an equlibrium. The emissivity of a tungsten filament is about epsO. abc How long does it take to heat the filament to this temperature? Ase that the radiation can be neglected during the heat-up time. abcliste
Solution:
abcliste abc The power emitted as radiation is given by P I A where I is the ensity of the radiation and A the surface area of the filament. The ensity is given by I epsilonsigma T^ where epsilon is the emissivity of tungsten sigma the Stefan-Boltzmann constant and T the surface temperature of the filament. The surface area surface of an open cylinder can be expressed as A pi d L It follows for the power P epsilon sigma T^ pi d L Solving for the temperature yields T TF leftfracPeps times ncS times pi times d times Lright^/ T approx resultTP abc The energy absorbed by the filament can be expressed as P Delta t c m Delta T c sscrhoW pi d/^ L Delta T where c is the specific heat of tungsten sscrhoW the density of tungsten and Delta T the temperature increase. Solving for the time yields Delta t tF fraccWo times RWo times pi times d^ times L times T - Tr times P t approx resulttP- abcliste
A typical incandescent light bulb with a power of PO has a tungsten filament with length LO and diameter dO. abcliste abc When the light bulb is on the electric power is converted to radiation. Calculate the temperature of the filament that allows for an equlibrium. The emissivity of a tungsten filament is about epsO. abc How long does it take to heat the filament to this temperature? Ase that the radiation can be neglected during the heat-up time. abcliste
Solution:
abcliste abc The power emitted as radiation is given by P I A where I is the ensity of the radiation and A the surface area of the filament. The ensity is given by I epsilonsigma T^ where epsilon is the emissivity of tungsten sigma the Stefan-Boltzmann constant and T the surface temperature of the filament. The surface area surface of an open cylinder can be expressed as A pi d L It follows for the power P epsilon sigma T^ pi d L Solving for the temperature yields T TF leftfracPeps times ncS times pi times d times Lright^/ T approx resultTP abc The energy absorbed by the filament can be expressed as P Delta t c m Delta T c sscrhoW pi d/^ L Delta T where c is the specific heat of tungsten sscrhoW the density of tungsten and Delta T the temperature increase. Solving for the time yields Delta t tF fraccWo times RWo times pi times d^ times L times T - Tr times P t approx resulttP- abcliste
Meta Information
Exercise:
A typical incandescent light bulb with a power of PO has a tungsten filament with length LO and diameter dO. abcliste abc When the light bulb is on the electric power is converted to radiation. Calculate the temperature of the filament that allows for an equlibrium. The emissivity of a tungsten filament is about epsO. abc How long does it take to heat the filament to this temperature? Ase that the radiation can be neglected during the heat-up time. abcliste
Solution:
abcliste abc The power emitted as radiation is given by P I A where I is the ensity of the radiation and A the surface area of the filament. The ensity is given by I epsilonsigma T^ where epsilon is the emissivity of tungsten sigma the Stefan-Boltzmann constant and T the surface temperature of the filament. The surface area surface of an open cylinder can be expressed as A pi d L It follows for the power P epsilon sigma T^ pi d L Solving for the temperature yields T TF leftfracPeps times ncS times pi times d times Lright^/ T approx resultTP abc The energy absorbed by the filament can be expressed as P Delta t c m Delta T c sscrhoW pi d/^ L Delta T where c is the specific heat of tungsten sscrhoW the density of tungsten and Delta T the temperature increase. Solving for the time yields Delta t tF fraccWo times RWo times pi times d^ times L times T - Tr times P t approx resulttP- abcliste
A typical incandescent light bulb with a power of PO has a tungsten filament with length LO and diameter dO. abcliste abc When the light bulb is on the electric power is converted to radiation. Calculate the temperature of the filament that allows for an equlibrium. The emissivity of a tungsten filament is about epsO. abc How long does it take to heat the filament to this temperature? Ase that the radiation can be neglected during the heat-up time. abcliste
Solution:
abcliste abc The power emitted as radiation is given by P I A where I is the ensity of the radiation and A the surface area of the filament. The ensity is given by I epsilonsigma T^ where epsilon is the emissivity of tungsten sigma the Stefan-Boltzmann constant and T the surface temperature of the filament. The surface area surface of an open cylinder can be expressed as A pi d L It follows for the power P epsilon sigma T^ pi d L Solving for the temperature yields T TF leftfracPeps times ncS times pi times d times Lright^/ T approx resultTP abc The energy absorbed by the filament can be expressed as P Delta t c m Delta T c sscrhoW pi d/^ L Delta T where c is the specific heat of tungsten sscrhoW the density of tungsten and Delta T the temperature increase. Solving for the time yields Delta t tF fraccWo times RWo times pi times d^ times L times T - Tr times P t approx resulttP- abcliste
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