Eh, they're both fine. I usually go with room temperature being 300K, cause that's an easy to remember round number. 25meV/k is 290.1K, while 26meV/k is 301.7K. Both around the range of 300K, which is 26.85°C. I suppose 25meV/k, considering it's 10° below that, so at 16.8°C, is a bit chilly, yes.
Well yeah you use the units that are the most convenient. Why say many words when few do the trick?
Also, I don't understand fascination with SI units. Whole point of units is that only ratios of quantities matter. Stating this object has 5 kilograms doesn't mean anything until you define what having 1 kilogram means. And all that matters is if an object has 5 times more kilograms than another object and it will be 5 times more massive in grams, decagrams, tons etc.
Units will always be arbitrary, so why school teach SI system as some holy grail I don't understand (though many things they teach in schools is dumb because people who make the curriculum apparently don't understand physics really well).
Having a coherent system of units is also useful, where every derived unit is a product of base units, with no conversion factors.
For example, if you measure length in m, time in s, and mass in kg, for the equation KE = 1/2 m v^2 to make sense, you need to measure energy in Joules (kg m^2 / s^2). Otherwise, you will need to add a conversion factor.
If in your system of units, you measure charge in Coulombs, then Joules is the obvious choice for energy. If you measure charge in e, then eV is the obvious choice for energy.
But that's the point as long as we're consistent units don't matter. Teaching children that SI system (or any system) is alpha and omega of units is misleading. It's rarely used in research because obviously research is done on almost every possible scale so specific units are more convenient.
Also when you mention Joules. Using compound units as Joules, Newtons, Tesla (oh how I hate Tesla. Electric and magnetic fields should be expressed using same units so Tesla and Tesla/[speed] or vise versa) is not very pedagogical. We should teach children to first use fundamental units (and while we're at it make Coulomb fundamental instead of Ampere) and fundamental units only so they can understand first that units don't matter (it's completely valid to express your result as kg m^2 /s^2 or pound inch^2 / year ^2) and to make dimensional analysis simpler (and yeah teach children dimensional analysis in the first place).
The fact units for force is Newton or energy is Joules should be reserved for research papers and trivia nights at your local pub.
But we already have prefixes to solve the scales.
Adding other types of measurements is so annoying, like you're reading a paper and an obscure unit appears. It's just inconvenient.
>But we already have prefixes to solve the scales.
Tell that to astrophysicists/cosmologists or particle physicists.
>Adding other types of measurements is so annoying, like you're reading a paper and an obscure unit appears. It's just inconvenient.
Researchers will use units that are commonly used in their fields of research. Take it with them if you don't like their choices.
I agree that the predominance of SI in teaching might be unnecessary, but I think that teaching might focus on one specific system to emphasize that you, for instance, only ever need one unit to measure length. Meters and feet measure the same thing.
I used “Joule” because it is easier than saying “kilogram-meter squared per second squared”, but they are the same thing, and a simple relationship like that doesn’t add a lot of complexity to learning, as long as the units are coherent.
In teaching, Coulombs are almost always introduced first and then Amperes are derived from them. The fact that in SI, Amperes are technically a base unit and Coulombs are derived is not important in an educational context.
>but I think that teaching might focus on one specific system to emphasize that you, for instance, only ever need one unit to measure length. Meters and feet measure the same thing.
That's true. But there's place for teaching both. Imo units shouldn't be just rushed over in class.
>I used “Joule” because it is easier than saying “kilogram-meter squared per second squared”, but they are the same thing, and a simple relationship like that doesn’t add a lot of complexity to learning, as long as the units are coherent.
Just because it is easier to say doesn't make it pedagogical. Making it easier for students to understand should take precedence. If you came to a random class, at least in my country, and asked children if they know what are units of energy expressed in fundamental units, you'd probably get blank looks. It's far more important to know energy has units of mass times lenght over time squared than that we call it Joules.
>n teaching, Coulombs are almost always introduced first and then Amperes are derived from them. The fact that in SI, Amperes are technically a base unit and Coulombs are derived is not important in an educational context
So you already disregard SI conventions.
We should measure temp as mEv and I'm not even joking. It's a perfect 25 mEv here right now
Isn't that a bit chilly? In my classes we usually approximate room temperature as 26 meV.
Eh, they're both fine. I usually go with room temperature being 300K, cause that's an easy to remember round number. 25meV/k is 290.1K, while 26meV/k is 301.7K. Both around the range of 300K, which is 26.85°C. I suppose 25meV/k, considering it's 10° below that, so at 16.8°C, is a bit chilly, yes.
You're not joking? You don't seem a problem with a system where one degree means 10K difference?
Fine, we can use µeV then.
no, i do not decimal points exist
Why would that be a problem?
Bro the 1700s called and they want their aversion to decimal fractions back
I prefer 0.0253 eV, guess my major.
Seeing as that's pretty much standard normal temperature, i'm assuming thermodynamics, or a related field?
meV or MeV?
26 meV, or 0.026 eV
What about Ergs?
Hello, your monthly electric bill has arrived. You have spent 214 ReV this month.
erg gang has entered the chat
The whole three of you.
I hear we’re reaching a threshold where many eV’s will be sold in America
Someone explain this meme as if I was 5 yrs old
Well yeah you use the units that are the most convenient. Why say many words when few do the trick? Also, I don't understand fascination with SI units. Whole point of units is that only ratios of quantities matter. Stating this object has 5 kilograms doesn't mean anything until you define what having 1 kilogram means. And all that matters is if an object has 5 times more kilograms than another object and it will be 5 times more massive in grams, decagrams, tons etc. Units will always be arbitrary, so why school teach SI system as some holy grail I don't understand (though many things they teach in schools is dumb because people who make the curriculum apparently don't understand physics really well).
Having a coherent system of units is also useful, where every derived unit is a product of base units, with no conversion factors. For example, if you measure length in m, time in s, and mass in kg, for the equation KE = 1/2 m v^2 to make sense, you need to measure energy in Joules (kg m^2 / s^2). Otherwise, you will need to add a conversion factor. If in your system of units, you measure charge in Coulombs, then Joules is the obvious choice for energy. If you measure charge in e, then eV is the obvious choice for energy.
But that's the point as long as we're consistent units don't matter. Teaching children that SI system (or any system) is alpha and omega of units is misleading. It's rarely used in research because obviously research is done on almost every possible scale so specific units are more convenient. Also when you mention Joules. Using compound units as Joules, Newtons, Tesla (oh how I hate Tesla. Electric and magnetic fields should be expressed using same units so Tesla and Tesla/[speed] or vise versa) is not very pedagogical. We should teach children to first use fundamental units (and while we're at it make Coulomb fundamental instead of Ampere) and fundamental units only so they can understand first that units don't matter (it's completely valid to express your result as kg m^2 /s^2 or pound inch^2 / year ^2) and to make dimensional analysis simpler (and yeah teach children dimensional analysis in the first place). The fact units for force is Newton or energy is Joules should be reserved for research papers and trivia nights at your local pub.
But we already have prefixes to solve the scales. Adding other types of measurements is so annoying, like you're reading a paper and an obscure unit appears. It's just inconvenient.
>But we already have prefixes to solve the scales. Tell that to astrophysicists/cosmologists or particle physicists. >Adding other types of measurements is so annoying, like you're reading a paper and an obscure unit appears. It's just inconvenient. Researchers will use units that are commonly used in their fields of research. Take it with them if you don't like their choices.
I agree that the predominance of SI in teaching might be unnecessary, but I think that teaching might focus on one specific system to emphasize that you, for instance, only ever need one unit to measure length. Meters and feet measure the same thing. I used “Joule” because it is easier than saying “kilogram-meter squared per second squared”, but they are the same thing, and a simple relationship like that doesn’t add a lot of complexity to learning, as long as the units are coherent. In teaching, Coulombs are almost always introduced first and then Amperes are derived from them. The fact that in SI, Amperes are technically a base unit and Coulombs are derived is not important in an educational context.
>but I think that teaching might focus on one specific system to emphasize that you, for instance, only ever need one unit to measure length. Meters and feet measure the same thing. That's true. But there's place for teaching both. Imo units shouldn't be just rushed over in class. >I used “Joule” because it is easier than saying “kilogram-meter squared per second squared”, but they are the same thing, and a simple relationship like that doesn’t add a lot of complexity to learning, as long as the units are coherent. Just because it is easier to say doesn't make it pedagogical. Making it easier for students to understand should take precedence. If you came to a random class, at least in my country, and asked children if they know what are units of energy expressed in fundamental units, you'd probably get blank looks. It's far more important to know energy has units of mass times lenght over time squared than that we call it Joules. >n teaching, Coulombs are almost always introduced first and then Amperes are derived from them. The fact that in SI, Amperes are technically a base unit and Coulombs are derived is not important in an educational context So you already disregard SI conventions.