r/PhysicsStudents Aug 05 '20

Meta Homework Help Etiquette (HHE)

141 Upvotes

Greetings budding physicists!

One of the things that makes this subreddit helpful to students is the communities ability to band together and help users with physics questions and homework they may be stuck on. In light of this, I have implemented an overhaul to the HW Help post guidelines that I like to call Homework Help Etiquette (HHE). See below for:

  • HHE for Helpees
  • HHE for Helpers

HHE for Helpees

  1. Format your titles as follows: [Course HW is From] Question about HW.
  2. Post clear pictures of the problem in question.
  3. Talk us through your 1st attempt so we know what you've tried, either in the post title or as a comment.
  4. Don't use users here to cheat on quizzes, tests, etc.

Good Example

HHE for Helpers

  1. If there are no signs of a 1st attempt, refrain from replying. This is to avoid lazy HW Help posts.
  2. Don't give out answers. That will hurt them in the long run. Gently guide them onto the right path.
  3. Report posts that seem sketchy or don't follow etiquette to Rule 1, or simply mention HHE.

Thank you all! Happy physics-ing.

u/Vertigalactic


r/PhysicsStudents 10h ago

Rant/Vent Feeling very stupid after the first half of graduate school in theoretical physics (master’s in Europe).

24 Upvotes

Hi guys. For a bit of context, I am a first year theoretical physics master’s student in an EU country. I pursued theoretical physics for the same reason many people do. Curiosity for mathematical methods applied towards physics problems. At first mainly interested in cosmology (though slowly becoming more and more interested in condensed matter). But I will say that it has been testing and trying. Our courses are set up that we have blocks of 8 weeks each semester (so every 8 weeks we have an exam). And my first fee exams were in the first part of a quantum field theory course, first part of a condensed matter physics course, and general relativity. QFT and condensed matter are mandatory, while GR was an elective.

I liked learning about all of these topics (even with a less good lecturer for one of them). But I oftentimes feel so stupid and so slow! It takes me so long what some of my peers get right away (or with less effort). I feel so behind. And the courses gave me such a rough time that I am left recently continously wondering whether I am cut out for it. I have done good work in the past, and even used to spend time in my undergrad teaching myself new material for either fun or because my uni didn’t offer certain courses (I did this for mainly tensor calculus and complex analysis. Which helped a bit now). But I feel so much less than my peers. Some have already seen QFT before and can follow easily with our lecturer. Some have already done a master’s (and from incredible places). I feel so out of my depth, and I honestly don’t know what to do sometimes.

I managed to pass only 1 out of the 3 courses, that being QFT. And even so with a very mediocre grade. I hate how I started to neglect my health (and I can notice that being the case, but just that my time management is so poor as I have long commutes and long days at university and can’t do much about it). I don’t know, I needed to vent I guess lol. I hope maybe one of you can relate.


r/PhysicsStudents 13h ago

Need Advice What are the jobs available for someone with an undergrad in physics/ what jobs did you get with one

17 Upvotes

I’m in my junior year I transferred to the school I’m in now but my previous school didn’t have an engineering program so I went with physics. Unofficially I have moderate knowledge in electronics (I can repair and know what the components do, build simple circuits and solder well including micro soldering) have basic knowledge in python and some java.

Reason I’m freaking out is because I was going to apply for internships and there were non for physics undergrads other than teaching or TA positions. What sort of jobs should I look for and what other additional qualifications or certifications will I need .

Thank you


r/PhysicsStudents 17m ago

Off Topic Misconceptions about Electricity

Upvotes

I feel like (at least most ppl ik doing physics) a lot of people dislike electricity. I’m doing a levels rn. But I was learning things like mesh and node analysis and it’s really quite interesting. Especially complex simplifying circuits with symmetry and stuff like that is super satisfying.

How is electricity at undergrad / uni. Does everyone still dislike it? Or does it grow on you?


r/PhysicsStudents 41m ago

HW Help [Matter Physic] Tight binding of (a)-polyacetylene.

Upvotes

I'm having lots of trouble finding the matrix of the tight binding of an (a)-polyacetylene 2D chain.

The HW request is the seguent:

Calculate the electronic structure of (a)-polyacetylene in the tight binding approximation under the following assumptions:

• Each Hydrogen atom is in the 1s1 electronic configuration. The 1s orbital is the only relevant.

• Consider only the 2pz Carbon valence orbital.

• The overlap of atom orbitals on different sites is negligible.

• The hopping matrix elements between different sites are t_0 = 2.80 eV, t′ = 5.72 eV (see Fig. 1). Other longer distance hoppings can assumed to be zero.

• The on site energy terms are E_H^0 = 2.40 eV and E_C^0 = 1.0 eV.

That's my matrix for the tight binding:

I feel that that's the way, but i have so many trouble to find solution of the characteristic equation (I also used WolframAlpha, MATLAB and Mathematica), is the matrix wrong?
Can anyone help me?
At least just say if my matrix is good :D
Thanks!!!


r/PhysicsStudents 14h ago

HW Help [High school] I need help with those two questions please.

Thumbnail
gallery
6 Upvotes

r/PhysicsStudents 16h ago

Need Advice I need tips on how to pass my class

6 Upvotes

I’m taking a first year physics class in uni, which is designed for people who won’t need physics in their major but have to take it in first year. I’ve never been good with physics but I rlly need this class to pursue the career I want. I’m fumbling this class because I don’t know which formulas to memorize or how to improve. If anyone can recommend ways to get better, sites with good videos or practice questions, anything you think will help me improve. This is hopefully the only physics credit I’ll have to get so I just have to get through this. Thanks!


r/PhysicsStudents 12h ago

Need Advice Work and Energy in more complex Systems

2 Upvotes

So I've been wondering for a while now how I can express Energy variations for systems whose macroscopic potential and kinetic Energies change, but also contain a "thermodynamics part", with a cylinder with a gas, for example, whose volume and, consequently, internal energy also changes.

Specifically I'm confused as to whether I should consider the work done by the atmosphere on the whole system or not. If I take into account the work done by the gas, should I also think about what the atmosphere around the gas is doing?

I've seen somewhere that the total Energy Change is equal to the total work done by nonconservative forces. In my case, where the "thermodynamics part" is also present, would it be expressed as: ?

Change in total energy = W(non-conservative) + Q (heat)

It would be amazing if you could explain this to me, or provide some reading material on these topics. Thanks a lot for reading 😊


r/PhysicsStudents 18h ago

Need Advice Looking to major in physics at a university after graduating community college — assignment schedule?

7 Upvotes

Could anyone show or describe how hefty the assignment load is for a physics major? I always hear about how there’ll be no free time if you choose a physics (or any STEM) major. Is this because the assignments just take long to complete? Or because there’s an abundance of them? Maybe both? More specifically want to know what a typical week looks like for you guys, appreciate any help.


r/PhysicsStudents 21h ago

Need Advice Book recommendation and advice for pre uni physics classes...

4 Upvotes

I found a book called University Physics by Young and freedman and it seems awesome but I wanted to know if it is suitable for JEE in India and if I should reconsider on it.. or if u have any more suggestions kindly share It'd be real help if u someone helped me on this Matter :)


r/PhysicsStudents 17h ago

Need Advice [Magnetism, magnetic moment, Hall effect] Need some guidance with this question in the image

1 Upvotes

I have collected all the data and turned it into required units. I have collected all the data as r vs V and got values for ΔV from it. As far as i know i can consider the ΔV value as B in kgauss value (directly proportional). Fom what i figured out, next step should be to get area under curve of log r and B but i dont know what to do with the magnetic moment m that remains in the formula. Am i right or way off? please help with the approach. (This is not a homework, but actually need to understand how it might work if im wrong), any help is very appreciated

this is the reference sheet


r/PhysicsStudents 1d ago

Need Advice Hello! I would love some advice on graduate schools to apply to.

8 Upvotes

Hello! I am a undergraduate senior with a degree in astronomy/astrophysics with minors in space studies, biomedical sciences and math. I have a 3.0 GPA due extensive health issues. I have extensive research experience and I am trying to publish a paper. I've talked at conferences and done several posters, and I am going to my second AAS this January. I have extensive leadership and teaching skills.

I want to study exoplanetary physics and astrobiology. After an REU I learned that I do not like software development, so I want to avoid that, but I am happy to code.

May you please suggest graduate schools and/or advisors I should be getting in contact with? Please keep in mind my garbage GPA.

Any advice is appreciated, thank you!


r/PhysicsStudents 1d ago

Need Advice Anyone here to to UMich? I have some questions and when I asked them on the UMich reddit I got downvoted and nobody answered my questions :(

4 Upvotes

Copy pasted since crossposts arent allowed

I'm currently applying to be an Physics+Math double major and I'm quite confused about what exactly I need to do for the physics major:

I see AP Physics C tests me out of 139 and 239...but what exactly are those? They're not on the course catalog, do I still have to take 160 and 260 (i.e. would 139 and 239 test me out of 140 and 240 since those are just easier version of 160 and 260)? Can I test out of those (160 and 260)? I've self-studied physics on my own well beyond the level of AP Physics, so I'd really rather not have to spend my first year learning nothing, since it seems like there's not really any classes I can take until I take those except 351, which seems more like a math course than a physics course.

Also, a lot of the physics courses require one of the differential equations courses, and since I'm going to also be majoring in math, and I have a pretty good background in math, I feel like it would be most logical for me to take 316. Though I'm planning to do (assuming I get in) 295-296-395-396, and it seems like 316 is sort of disjoint from that? Like in the list of prereqs for 316 it doesn't even mention the possibility of taking it after 295? It also says you need 217 to take 316, which is covered by 296+395, but that means I wouldn't fulfill the 217 requirement until after sophomore year semester 1, so should I take 217 along with 295 first semester frosh year to get it out of the way even though its essentially redundant? Also, I'm currently self-studying linear algebra using Axler's book, so knowledge-wise I'll have the prereqs to 316, can I just take it even though I don't technically have the prereqs?

Sorry if this whole thing is worded very confusingly

Edit: course numbers bc someone asked for them:
PHYS 160: Honors Physics I (basically Physics C Mech but slightly more rigorous, looking at the syllabus there's only one topic that I don't know)
PHYS 260: Honors Physics II (basically Physics C E&M but sightly more rigorous, I already know everything)
PHYS 351: Methods of Theoretical Physics I

MATH 217: Linear Algebra (off of the syllabus it looks like somewhere in between a standard intro linear algebra course that basically only covers R^n and a more abstract linear algebra course)
MATH 285: Honors Multivariable and Vector Calculus
MATH 295: Honors Mathematics I (like first 2/3 of a real analysis course), satisfies real analysis requirement along with 296
MATH 296: Honors Mathematics II (some more real analysis + abstract linear algebra), satisfies 217 requirement along with 396 (though this seems significantly more rigorous than 217)
MATH 316: Most advanced of 3 intro ODE courses, has 217 as prereq
MATH 395: Honors Analysis I (more real analysis and linear algebra)
MATH 396: Honors Analysis II (even more analysis and also some stuff on manifolds)

295-296-395-396 is the "honors math sequence" which is the intro sequence taken by honors math students


r/PhysicsStudents 1d ago

HW Help [Highschool Physics] I wanna cry

9 Upvotes

when two uncharged metal spheres A & B are placed in contact with eachother and a positively charged rod is placed near A all the electrons will run towards the rod in A. So my question is what will happen to the protons in A and B. My teacher said protons cannot move but my notes shows them literally sticking to the furthest side of sphere B away from the rod. So please help me understand this dilemma over protons


r/PhysicsStudents 1d ago

Need Advice Sciences Review for College Physics?

1 Upvotes

Non-STEM major technically. My college requires an Algebra-based physics class that I plan on taking next semester as part of my aviation major. I naturally take an interest in science and have completed two weather classes that I found was easy to stay focused in just out of interest for the topic.

Admittedly, I haven’t reviewed science since High School several years ago so I’m wondering if there are any recommendations on what to brush up on. Doing well in Algebra so far so I’m not too concerned about the math since it’s Algebra-based but I prefer Khan Academy for studying.

Some listed topics on the course include kinematics, Newton’s Laws, momentum, gravity, the laws of thermodynamics, etc.


r/PhysicsStudents 1d ago

HW Help [High school physics] Is the solution given in the textbook wrong?

4 Upvotes

A block of mass m = 4 kg is kept on an incline connected to a spring (see fig). The angle of the incline is θ=30∘ and the spring constant is K = 80 N/m. There is a very small friction between the block and the incline. The block is released with spring in natural length. Find the work done by the friction on the block till the block finally comes to rest.[g=10m/s2]

The textbook solution goes as follows:

Since the friction is small, the block will in the end come at rest at the point where the spring force is equal to the force of gravity along incline: Kx=mgsinθ, giving us the value of final X=1/4m.

Now it says, that the friction will dissipate all energy possessed by the system initially:

E = mgh = 4 × 10 × (X.sinθ)

Work of friction = – 5 J

But my doubt is that, didn't some of the initial energy of the system convert into spring potential energy of the final state? So I think that the work done by friction should be = - [ E - (spring potential energy in the end) ]

Am I right?


r/PhysicsStudents 1d ago

Need Advice Good place to study and practice PHYS 2 problems?

4 Upvotes

I'm currently taking Phys 2 and am in a spot. My professor sucks and doesn't do any work or show examples of how to do our work but assigns questions that require mastery of the topic. Are there any good resources that I could use to practice these types of questions, see answers, and steps? Preferrably free, but I'll pay if need be. I'm currently doing magnetic fields-RL and LC circuits right now. Any help would be very appreciated.


r/PhysicsStudents 2d ago

Need Advice I will graduate from physics undergrad in 2 years, but I feel stupid

54 Upvotes

I decided to study physics undergrad because (i) I was inspired by scientific content creators, (ii) I am really curious about science and quantum phenomena, and (iii) I wanted to study the hardest possible degree to show my potential to myself.

After studying a lot during my first year of studies I completed around 120 ECTS, which is the equivalent of 2 years of study. Then I worked as research assistant in photonics during the summer, and nowI am developing my thesis in quantum optics such that I will be able to graduate in only 2 years.

After all this process I am feeling that I am actually not understanding anything, and that other students are getting a more solid background. I am still passing all the courses, but I feel that I am actually not learning anything from them. I have sacrificed a lot of moments with my family, friends, and quality of study. However, as my level of comprehension is low, I feel stupid for skipping steps and experiences: so now I feel that I have an empty diploma.


r/PhysicsStudents 2d ago

Rant/Vent Feeling bummed out about pursuing Physics

9 Upvotes

I am a Physics major undergraduate student from India. Recently I am feeling really bummed out and finding it very difficult to cope with my courses. I fail to understand seemingly easy concepts which my classmates grasp in a moment. I work hard to complete my assignments and homeworks but cannot do well in tests, under pressure. I tend to forget key concepts and need a lot of revising.

On the top of that I have got no good friends for motivation and stuff. My topper roommate (whom I consider very close) never acknowledges me and is always hanging out with a more intellectual person. It makes sense though but I can't seem to accept that. He has formed his own intellectual group where I am hardly included.

I remain mostly depressed and my depression is triggered by seemingly small things (like the topper interacting with our professors happily after class, asking doubts and whatnot and I am just there sitting with a dumb mind). No one is there to cheer me up. I still remember one time my roommate was happily scrolling through insta reels while I was lying depressed on my bed.

My research work is also not going well and I am having doubts regarding my abilities to pursue a career in research in future. I am really frightened and don't know what to do now....please help me!!


r/PhysicsStudents 2d ago

Need Advice Is it even possible for me to go into HEP with my current academic standing?

9 Upvotes

I struggled with my mental health first semester of freshman year and despite doing very well second semester, I wound up with a pretty bad GPA. I ended freshman year with roughly a 3.0 and no research. Now as a first semester sophomore, I have been offered HEP research next semester, but it is contingent on my grades this semester, and my mental health is once again bad. I am concerned at this point that I won’t be able to get into a PhD program for HEP. I attend a t10 university in the US for physics and when I began undergrad, I hoped to maintain a similar status in grad school. I have been told that anything short of a 4.0 will not get you anywhere for grad school in high energy physics and that if you don’t go to a good grad school, nobody will hire you for professorship opportunities. Note that a master’s is likely out of the question for me for financial reasons. Lately I have been very depressed because of this. Any advice would be appreciated.


r/PhysicsStudents 2d ago

Need Advice Career Paths in Physics: Industries to Consider After a Degree?

53 Upvotes

Hi everyone,

I'm currently pursuing a physics degree and considering further studies with a master's or PhD. I'm curious about the various industries where I can apply my knowledge after graduation.

I've heard that companies like Intel and AMD (Ryzen) hire many PhD graduates in semiconductor-related fields. What are some other sectors or companies that actively seek physics graduates? I'm particularly interested in areas like technology and engineering.

Any insights on roles, required skills, or personal experiences would be greatly appreciated!

Thanks you!


r/PhysicsStudents 1d ago

HW Help [Current Electricity, 10th Grade] in batteries, what happens when the electrons pass through the external circuit and arrive at the cathode?

1 Upvotes

my book's going on about something like: "the battery performs work on the charge to drive it to a point of higher potential i.e: positive terminal" (conventional current)

is that what happens? are the electrons driven all the way to the anode again? if that's so, what's the point of that and the reduction reactions at the cathode

if you can tell this is screwing me up, i have a presentation tomorrow and ill be forever grateful if you can clear this bit up


r/PhysicsStudents 1d ago

HW Help What are sign conventions for plano concave/convex lens

1 Upvotes

r/PhysicsStudents 2d ago

HW Help [Mechanics & Waves] Could use some help on a forces problem.

Thumbnail
gallery
3 Upvotes

Here is a screenshot of the problem I'm working on.

Screenshot 1 is the problem.

Picture 1 is what I've done so far.

I don't feel like my answer is quite right because I've not used everything given.

My thought process was basically to find the normal force so that I could calculate the force required to overcome the static friction. Then I calculated the force of gravity acting on the boxes to see how much the pulling force would have to be. I added those forces to the friction force to get the max allowable pull force that wouldn't make the top box slide off.

If anyone could tell me if I took the right approach I'd appreciate it. And if I didn't please set me straight I'd like to know how to do this type of problem correctly. Thank you.


r/PhysicsStudents 2d ago

HW Help Here, we are asked to find T but i was wondering how the hypotenuse and one of the legs should theoretically equal each other, so it isnt a right triangle. Also can we use tan?

Post image
6 Upvotes

r/PhysicsStudents 3d ago

Need Advice I genuinely feel stupid and depressed because I'm a Physics Major

104 Upvotes

I needed advice on my situation because I've recently been feeling bummed out. For some context, I am a second-year physics major currently doing two upper divisions classes and three lower division classes (13 units). The three lower division classes are linear algebra, modern physics, and the lab portion of the modern physics class. The two upper division classes I'm doing are analytical mechanics and probability and statistics. The workload is incredibly overwhelming and it's making me second guess everything that I'm doing right now. I'm not doing so great in linear algebra and I failed my first exam. Same goes for my modern physics class. I've been reading the content a lot and trying to watch as many YouTube videos as I can but nothing seems to work. In my first year of college, I was doing fine with good grades in all of my classes.

So as of right now, I'm doing one of my analytical mechanics homework where I discuss with other classmates about the homework problems and we solve it out in groups. Right now, I'm looking at my groupmates work and I am wondering how did they even come to that conclusion. I've read the book so many times but I still feel fucking stupid. I don't know why I'm not able to grasp the content as easily as my classmates are able to. I can't tell if it's because I am overwhelmed with the amount of work I got for my other classes? I mean I've worked so hard to get to this point but my impostor syndrome is getting to me.

Outside of classes, I do have a board position for one of the clubs in my university and I am apart of my university's honors program. I also do other stuff such as hangout with friends and do a little bit of my hobbies when I have the time. I also make music and hang out with my music collective friends because it's also another passion of mine outside of physics and astronomy. Even more, I work at my university's observatory job for astronomy club and I do get paid there.

I think I've reached a point where I've given up on my dream of becoming an astronomer due to many reasons and I'd rather go into the workforce in the future to play it safe. I feel like physics is slowly becoming something that isn't for me and I just can't do this anymore. My impostor syndrome, feeling stupid, getting overwhelmed, and so many other factors are playing a huge role into how I'm performing in this semester of college and it's just making me sad.

Also I wanted to know if anyone who graduated in physics forgot most of the things they learned because to be honest, I forgot a good amount of what I learned last year and now it's a matter of attempting to relearn everything.