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  1. J

    Thermocouple connection

    So, it's been confirmed that one end has to be a junction, or else the thermocouple will not work well. But I still have no explanation for why this is so.
  2. J

    Thermocouple connection

    I want to measure the temperature of a metal stage where I am holding a sample. What I have done is to clamp both wires from a thermocouple against the stage using a bolt and washer. Supposedly this is not the best practice but I don't see why this would be a problem. I have read that you are...
  3. J

    Programs Is an engineering degree worth going into depression for?

    Because he ASKED for advice, and that's what everyone here is giving him. You obviously have a problem with what I said, but I see nothing wrong with it. I said medications are not the answer to real emotional problems. That doesn't imply that they are never the answer, and I don't see how...
  4. J

    Programs Is an engineering degree worth going into depression for?

    Well first of all, I even started my post with a caveat that I shouldn't advise him without knowing him. Others have advised him to take the drugs. Isn't that equally bad given that they know as little as I do about the situation? I said to "be wary", not to ignore all doctors. If you ask...
  5. J

    If sound travels faster through solids then why can't we hear through doors?

    I'm not an acoustics expert, but there are reflection losses at the two interfaces between door and air, just as there are for light between two materials of significantly different refractive index. I would guess that's the main loss, but maybe someone else can correct me.
  6. J

    Programs Is an engineering degree worth going into depression for?

    Sure, engineering can be good for getting a job, but it's not like everyone else ends up lying in a ditch. And anyway, then the question becomes "is a job worth depression?". Only you can tell whether there is something else which you would rather be pursuing but are not. There is nothing...
  7. J

    Programs Is an engineering degree worth going into depression for?

    I'm no psychologist, and I don't feel I should really be advising you without knowing you. But it seems obvious where your problems are stemming from if you say your parents will think you are a failure unless you complete this task which is clearly not what you want to do. It is right for you...
  8. J

    Programs Questions about Undergrad Degree in Physics

    People can get into good graduate programs from pretty much any undergrad college or university, even if it isn't that highly ranked. There are a lot of schools out there. You know what the really prestigious schools are; beyond that just buy one of those big college guide books and do some...
  9. J

    Problems with physics labs

    I never felt comfortable in labs in undergrad, but I think I am fairly competent working in a REAL lab, on my own research. I would suggest trying to get some research experience before writing off experimental work entirely. Certain people take a little longer to understand hands on work than...
  10. J

    AP Phys, have i done something bad?

    It sounds like they are talking about a college physics course which students may place out of if they took AP Physics B. Since most students who go into science or engineering take AP Physics B in high school, such a college course is usually taken by non-majors who just need to fill a...
  11. J

    AP Phys, have i done something bad?

    I have no idea where you heard that AP Phys B was a bad choice for engineering. It's not possible to be a competent engineer of any type without a solid understanding of that material, in fact it's only scratching the surface of what you need to know. For mech E/aeronautical, chem will help...
  12. J

    Am I actually learning Calculus?

    In my high school students did not take calculus until their final year (12), even if they were strong in math. Year 11 was precalculus, covering the sort of things you are describing. Maybe more of the core calculus topics are covered next year.
  13. J

    Bad not to participate in activities outside classroom with fellow grad students?

    Why would you even ask this? You already have friends and you aren't interested - sounds like you made your mind up already.
  14. J

    Basic question regarding applied voltage and circuits

    What do you mean 2 kV isn't relative to anything? It's relative to ground, since the power supply is grounded. The metal sphere may have a small charge on it, but you can bet it is very nearly at ground as well, especially since it's been touched recently. It is not the case that you need to...
  15. J

    Why is work a scalar?

    Wikipedia, on the work-energy theorem: Why insist on understanding work without any reference to energy? Energy is the more fundamental quantity.
  16. J

    Basic question regarding applied voltage and circuits

    If the power supply has a "ground" output I would expect that to be grounded internally, so you shouldn't need to attach it to anything. Does it have a positive and negative output terminal? If so, I think it is common practice to connect one of these to ground. On some power supplies I have...
  17. J

    Best angle to blow on coffee?

    Did you have the coffee filled to the brim of the mug, so that the air would always hit the surface of the coffee and not hit the inside of the mug at low angles? Or did you have it filled to a level more characteristic of normal drinking practices? My coffee maker doesn't make the coffee...
  18. J

    Concerned that engineering might be cold and indifferent?

    If you enjoy the subject matter and you are interested in engineering, then study it. There is room for all sorts of people in engineering. But the description of engineering as "cold and indifferent" doesn't make it sound like you are engaged with the subject. Getting to work in groups of...
  19. J

    Is going to lecture a huge waste of time?

    What you're saying is that it's possible to do well without going to any lectures. I doubt anyone would deny that. That doesn't necessarily imply that lectures are a waste of time.
  20. J

    Conceptual question on field/displacement

    Ok, the answer is just to take the superposition of the fields from many dipoles. Everything should cancel except the field parallel to the polarization.
  21. J

    Can't understand what's thermal equilibrium

    If you have two systems which can exchange energy, but neither can do work on the other, thermal equilibrium is the state in which no net energy transfer takes place. It turns out one quantity has to be equal in both systems for this to occur, and we call this quantity the temperature.
  22. J

    Conceptual question on field/displacement

    I have a very basic problem in understanding the relationship between electric field and displacement. If a field is applied to a dielectric, it is clear that this will cause the material to polarize, and one can define the permittivity of the material to quantify the size of this effect...
  23. J

    New to Physics Forum and would like some help with concepts

    Draw a free body diagram, figure out the forces acting on the body, use Newton's laws.
  24. J

    What are the less challenging/competitive sub-fields of physics to get into?

    Well, I hate to speak this way about my own field. But those who like condensed matter can sometimes enter a materials science program as a "back up". You can still make it as rigorous as you want of course, that is all up to you. Choose the right research group and you can be working on...
  25. J

    Optical chopper

    Yeah that was unclear. I'm doing pump probe experiments, so you want to chop only one of your beams to minimize background (either scatter from the pump, or the signal generated by the probe alone). The pulses are <100 fs, so the only way to modulate the beam at something other than a...
  26. J

    Is going to lecture a huge waste of time?

    This comment seemed to draw a lot of criticism, but I have absolutely experienced this. I have met multiple people who wouldn't think of reading the book chapters. I studied the chapters front to back. Reading a book by yourself requires you to think harder - those who wouldn't read it are...
  27. J

    Optical chopper

    I'm not trying to be pedantic, just trying to understand you. So it's not really the case that the chopping frequency needs to be prime, it just needs to be some frequency that isn't heavily influenced by the 60 Hz hum. I suppose choosing a prime number is a decent way to meet this criterion...
  28. J

    Is the physics education system in the USA more hardcore/rigorous than in the UK?

    Well, I'm an American who studied in Cambridge for a year (materials science). And at least from that experience, it seemed that the philosophy is to cover a ridiculous amount of material very fast, and pat yourself on the back for how much more you cover than other universities. But students...
  29. J

    Optical chopper

    Sorry if I'm being slow, but I don't understand what you're saying at all. It sounds to me like you're arguing that some extraneous device in the lab is more likely to put out noise at an integer frequency than a random decimal frequency. Maybe I can buy that, but where do the harmonics come...
  30. J

    Is going to lecture a huge waste of time?

    Well, I missed a huge fraction of my lectures in undergrad - and mine weren't recorded. I found that most classes were either boring and too slow, or too fast so that all I could manage to do was scribble down the notes without understanding. Later I would be studying, but my handwriting is...
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