# This is what a theoretical physics exam looks like at university

Hey everyone, today i’m going to show you inside a physics exam. I know that some of you might be interested to know exactly what studying physics is like and therefore what sort of exams and assessment looks like. So I have here a theoretical physics exam and I will say as a disclaimer, the questions in here I have edited so that they’re not exactly the same as an exam I took although it is based on a real exam. I’ve done this for two reasons; one, so that my uni doesn’t arrest me for publishing a real exam and two, is so that I can give you guys some solutions as well that are sort of fully worked and available elsewhere online in like textbook solutions. Having said that it does cover the same ideas that you would expect and that I definitely saw when I took an exam like this for the first time. Now the exam i’ve replicated is a theoretical physics exam from a third-year university course and it would take you three hours to do this exam and there are four questions so let me show you what it looks like. So this exam is going to cover most areas of theoretical physics, that’s a bit of classical mechanics, some quantum mechanics and special relativity. So let’s have a look. First up we’re going to have a classical mechanics problem and this is one that deals with a lagrangian. So we’ve actually got a double pendulum here and this is probably a bit of a typical problem. So you’re given a double pendulum and you’re asked first of all to find the lagrangian. So that’s essentially a way of finding out how to describe the system when the system is quite complicated. Then you want to find the equations of motion, that’s probably where you’re going to get a lot of marks as well because they might be a bit complicated and there’ll be a lot of calculus involved. Then you’re asked to describe the properties of a chaotic system. That’ll be saying something like a chaotic system, which a double pendulum is, well small deviations in where it starts or in the initial condition can lead to vastly different outcomes over time. And then lastly for this question we’ve got, explain the significance of Noether’s theorem. Moving on to part two, now we have a quantum mechanics problem. So this is actually from Griffiths, a really good quantum mechanics textbook and it’s about time independent perturbation theory. Now often when you work with quantum mechanics problems you’re dealing with say, a particle in a Infinite square well but perturbation theory deals with if there is a sort of blip or a bump. A perturbation in that square well so it’s no longer just a perfect square. Have a look in the description and I will link the solution here of how to do this. Our third question is also a quantum mechanics problem, it’s dealing with some sort of identities, commutator relations and really it’s a whole bunch of proofs. When I was doing sort of this exam, getting to this page, the page of quantum mechanics proofs, and to show things, is where my heart sinks because those are to me the hardest questions. Using mathematical induction or otherwise show that this is true. The classic ‘or otherwise’ statement, means really do it using the way they mentioned at the start otherwise you’ve got some crazy idea up your sleeve, I don’t know. Maybe if you’re clever you can think of another way to do it but usually when they give you a hint like this it’s a good idea to go with the hint. Part C I would probably find pretty tricky in this exam and it’s showing a relation that’s got something to do with Ehrenfest theorem. I don’t know how to pronounce that, I barely remember that theorem but I know, this has got something to do with it. Then part D we’re finishing off with a question about spin. The spin question really comes down to using linear algebra and it’s a useful application of some of the maths you learn quite early on. So finding a normalization constant and expectation values. Lastly, we have one whole question about special relativity. What makes special relativity difficult in say third-year is not the idea of sort of time dilation, and length contraction but it’s moving into using tensors and describing things in four-space. So that’s you can see this little notation here with the greek letters. That’s called a four-vector and it can be pretty tricky and be an obstacle to actually describing sort of space-time and special relativity. So because of that and because you would have just learned how to use these four-vectors, most of these questions here are just sort of kind of manipulation of four-vectors and once you really master these I think you might be able to go on to being good at things like general relativity and really getting into deeper into theoretical physics concepts. That isn’t the road I went down, but I think they were still pretty cool to learn about. I hope no one gets too stressed out looking at this exam that i’ve showed you because whilst this is pretty realistic of what you can expect, if you haven’t taken the course and subjects that are relevant to what i’m showing you, it can probably look overwhelming. Even me looking back on this now i’m like, geez how did I do any of this? I can’t remember some of this stuff now. But when you’re in that mindset of learning and studying for a course then it’s not so alien to you, then something like this would feel possible if you’re actually immersed in that environment and you’ve done the work leading up to it. Thanks for watching and if you have any questions about this exam or what others might look, like please let me know.

Does this look like something you would enjoy? 😂

I love you mam

2:35 “Explain the signficance of Noether’s Theorem”

cuts away immediatelyCan I call myself a theoretical physicist if my degree in physics is theoretical?

I love it Universe,Life,Matter,Energy and infinity,greetings from México.thanks very much for you video.

Nerd

This is what a fuzucs exayam look layk

I have my theoretical electrodynamics and special relativity exam tomorrow :"') At least the first task on your exam looks familiar^^ You and your Videos are awesome!!! First thing I 'm going to do after the exam: To watch an other Video 😀

so u teach also..pls solve a problem on einstein twin paradox (special relativity theory)

I just wanna do Voice Overs, what am I doing here? hmm

Easy shit.

It's an undergrad level exam, probably a simple one, at least compare to the exams I have taken during those years.

Very beautiful girl 🙂

that cover is a reaction image

Fantastic has a degree in theoretical physics

Find the what?

Thank you for this!

I want to learn fezzix.

Theoretical physics, without experimentation, it's pure speculation any valueless.

I'd get -5/100 marks

this is actually pretty good, but like when i was in my undergraduate courses, I took an entire course on classical mechanics, one course on quantum mechanics and one course on special relativity topics. So, in this case, its kind of an introduction to theoretical physics?

Gordan Freeman would like to know your locationI have all the correct answers, but the questions are wrong!

I NEVER STUDIED PHYSICS BUT I LOVE IT, I DONT CARE HOW MUCH HOURS TRYING TO LEARNING IT, IM DECIDED TO STUDY IT. God, she is beutiful too.

Just a disclaimer – She is not from US. In US her kind don't do Theoritical Physics, Abstract Mathematics,… Accent looks like from NZL or OZ?

They all look very simple i mean if you dont like it dont take it. God built us for different reasons.

Dam this girl wasn't only smart enough to pass it, but she's gonna break the exam down for and explain how to get the answers! Girls a genius…

You sure are one of my most favorite physicists out there! I am only in 9th grade and I want to become a physicist because of your videos!

Mam I have written a research paper on dark energy.

Mam soon I will publish

No idea why this came up as a suggestion but yikes !! Lol 😜😂😆😜

ALL exam papers look like this, believe me

At the first question calling the conservation of energy for the double pendelum Noethers theorem is an overkill. I mean sure, the double pendelum is descibed by a 1 timelike and 0 spacelike dimensional field theory with two scalar fields, but come on. Or they are calling something Noethers theorem that I don't.

Only 1 hour to complete if on adderall

Hermione??!!!

To all who are saying that this is hard, it really isn't. Physics is bearable if you know the formulas. The "cracking of the code" lies with the understanding of the appropriate theorems and their applications.

Are You going to make a video on how to solve those examples? Best regards

ok this is waaaaay easier then what I remember

There's a really slick way to do part a on #3, I'll try to find it and post it

“This exam will take you three hours”

Ok…

“There are four questions”

…

not that hard though

I don't any theoretical physics, but honestly it doesn't look that hard if you take the class. I took a physics class which didn't even use calculus and there were a lot of difficult questions because the way the questions were designed. The math was never the hard part, but the questions were basically always story problems you would have to translate to mathematical equations.

How well would Sheldon Cooper do on this exam?

"Unify the quantum theory with general relativity for 5 marks. Oh, and explain"

Is there any overlap between applied physics and theoretical physics? just got into uni for applied physics and this looks so interesting, hoping I’ll get to learn it.

In my graduate electromagnetic course's final exam we had 4 questions for 3 hours (10'00-13'00). By 11'30 the professor somehow realized the exam was hard and he proposed to take the papers at 12'00, have a 1h break then to move on to another class to continue the exam at 13'00. Off course during the one hour break we had the chance to eat, look at our notebook or whatever, chat between ourselves. To resume I got out the exam by 14'15 and no one finished the exam at 15'00 despite all the extra help and time we got 😂😂😂. What's funny is that it wasn't a hard-impossible exam and the questions seemed easy and familiar (except the special relativity question no one saw coming 😂). And although we were a pretty good class this is the funniest exam I took

The form of question two also exists in the finance world when you price a derivatives product. Looks quite interesting but not something I could do without several years of study.

First video I've watched from you, and the first thing I thought was that you look and sound like Emma Watson 🙂

how did you start in physics, i would like to start myself i just have no clue where to begin

Would've scored full 0 points of that physics test.

it's not too bad until you start seeing the Christoffel symbols!! then its like (・o・) (・へ・) (@[email protected]) ヽ(｀д´；)ﾉ ’ ٩(๑òωó๑)۶ (ノ｀Д´)ノ彡┻━┻ ψ(｀∇´)ψ

3rd year undergrad physics. Memories.

3 hours for 4 questions? We only get an hour for a test like that at my university.

Its not that bad if you're actively learning the material. I got my degree last year and I probably couldn't do most of this now.

What class has all of these in a single exam? I'm in 3 separate classes for each of these subjects

To much rick and morty jokes but never watched it tbh

What type of exam is this? QE type of exam? In what module would you have a comprehensive theoretical physics exam? I mean dont you take QM exams in QM classes and CM in mechanics? Also the quality of the questions are not so good I think: Question 4 e) construct an invariant dot product: invariant to what? Probably Lorentz transformations, but why not say so? But the we knwo what dot product is invariant (the usual minkowski one). It would make more sense to construct

alldot products invariant under Lorentz transform.easy

You put the very best thumbnails for your videos lol😂

I remember doing Lagrangian Mechanics when I studied Physics at uni. Deriving the Lagrangian, L, would be relatively easy. Turning the handle on the calculus to actually find the differential equations takes time and is prone to mistakes.

Hello, physics student here, this exam is legitimately trivial. The double pendulum is almost every TA's go-to for tutorial 1 material in classical mechanics, and this "exam" only gets easier from there.

I guess it would be really easy

if I understood the questions

I have no idea why I thought this would end up being a joke. On the other hand, I love that this video exists, and wish YouTube had been around for things like this when I was an undergrad so I could have had a better idea how to choose an emphasis early on.

The first problem is analogous to a toroidal form. Nice quiz I am going to take mine at two weeks. Regards!

Watching this video makes me want to go back to university (to study physics)

I'm a dimwit and I like to keep it that way 👍

If you do a course called "Theoretical Physics" your uni doesn't have a good physics program.

This is Greek to me, literally.

watching this as a fourth year physics student makes me cry lmao

it's like a fckin flashback of my whole univ life*

Deym dont know how i got here. I just wanted to know how to compute distance travelled

As an astrophysicist myself, 3rd year quantum mechanics exams give me what I believe might be PTSD. Never, ever again my life. Ever.

I have absolutely no clue what you are describing, but your presentation is utterly charming and enjoyable.

Id imagine its much easier if you actually have been taking physics classes

I like that t-shirt

So eazy. Its is not theoretical minimum for theoretical physic, only for engineers and experimentatora

Try Delhi University MSc physics question papers on any of the subject you will enjoy it

"Question 1: Find the Lagrangian-"

I quit.

I get a feeling of immense anxiety when I click your vids

Are u related to Emma Watson???

this looks simple i took ib physics hl for 2 yrs and this doesnt look that intimidating to me

Some questions are relatively easy for a 3rd year student I guess. But some questions only takes 3 to 4 lines and of 4 Marks. But I enjoyed it!

Your whole channel is basically an exam review channel

When u said quantum mechanics, all i can think of is avengers endgame LOLOL

Tibees, I have a question, How do I get a brain like yours??? Any help is appreciated 🙂

I managed to pass my physics degree. I can't imagine how, there was a lot of coffee involved as I remember, I don't remember the maths.

You remind me of Samantha Carter from Stargate SG-1 TV Series. The exam you showed us is rather easy one.

Hi Tibees. Could you make unboxing quantum chemistry exam?

The answer is 42 😊❤️

I'm studying marine biology/ecology. I find it nice that I can actually see what I'm studying and comprehend the material. Theoretical physics is in my eyes a lot of hocus pocus that has yet to be proven.

Seriously your voice is very calming and it soothes me.

Oh no I’m wait no I’m not scared. Got my masters there let’s go!

Damn mine was a spherical pendulum. That took me to do a 25 page series math problem lol.. good video

You are exactly how I picture Hermione Granger.

Looking at the expression of ur face at the preview pic i suddenly realised that the video will be abt smth really Boring and difficult

P. S

Ur face's expressions are my favourites😂

She luks like emma watson

Those four-vector things look intimidating at first but should be somehow intuitive when you get to practice more… I guess… from someone who watched some GR lectures and realized knowing nothing about SR in the first place 😂

This looks super hard but I feel that with time and lots of practice you can do this better and even find it fun

I came here because of Dr. Sheldon Cooper. 😊

0:01 A poster of Schrödinger's cat in the backround.

I think that perturbation theory is probably one of the harder potential barrier QM problems that can be asked for although once you understand delta-function type potentials the problem is straightforward

Look there's a Schrödinger's Cat poster in the background 💖