Is it safe to heat my borosilicate erlenmeyer with a common lighter? Or will it cause thermal shock strong enough to break the flask? I brought it from Amazon, it doesn't specify any safe temperature limit.
Also is there any safe operating temperature chart for different glasswares?
48×48C0+49×49C1+50×50C2+...+100×100C52
I have to somehow simplify this to get the form 100×101C49 - 101C50
I'm looking for a sort of tier list of obscure/general knowledge that most people don't know about, and that people who do know about it usually don't want to advertise.
I'm not talking about personal information, passwords, hacking someone's account, etc. I mean general knowledge, weird loopholes, obscure scientific facts, engineering tricks, legal/technical loopholes, things like that.
For example:
- Mixing vinegar and bleach can produce toxic chlorine containing fumes. Two completely ordinary household chemicals, but the combination can be seriously dangerous.
- A cheap high voltage generator combined with a cathode ray/vacuum tube can potentially produce X rays, i.e ionising radiation. Something that sounds completely innocuous until you know the physics behind it.
- Or just weird loopholes in general rules where something is technically possible because the rule assumes a condition that isn't actually guaranteed.
Basically, I'm looking for the kind of information where you'd hear it and go “Wait, you're telling me this is actually possible?”
I just genuinely love collecting obscure information like this. Of course I'm not going to try dangerous stuff myself, I'm well aware that experimenting with things involving toxic gases, high voltage, ionising radiation, etc. is a pretty good way to injure or kill yourself.
So, what are some examples? Ideally stuff that's genuinely obscure rather than the usual “did you know magnets can make electricity?” type facts.
Bonus points for things that most people don't want you to know, but are completely legal/public knowledge if you know where to look.
Oreo Sandwich
Costed me about 50 cents
I’m currently in the 12th standard preparing for the upcoming WBJEE. During my off time, I’ve been researching branches, and I'm highly interested in electronics specifically core hardware and embedded systems. I really want to avoid heavy software coding and competitive programming, which is why I feel like th IEE branch at JU would be the perfect match for my goals.Since I'm setting my target ranks now, could yall let me know what the typical safe GMR is to secure IEE through the regular counselling rounds?Additionally, I’ve been reading up on the decentralized counselling process (the spot rounds that fill vacant seats after students leave for IITs/NITs). Does this process give a significant advantage for getting into IEE? For example, if I get a GMR of around 800 and barely miss IEE in the normal rounds, forcing me to take EE, is it realistic to expect an upgrade to IEE once college begins? I heard that the decentralized cutoffs for IEE can stretch up to 1000 to 1200 GMR. I’d love to know if that is true.Thanks a lot for your time and guidance!
Has everyone forgotten about LUVOIR?
I remember hearing about it years ago, around 2015–2016, while I was also hearing about JWST. I spent years waiting for JWST, and then finally watched the launch live on NASA’s YouTube channel in 2021.
Then I thought: Okay, JWST is finally up. Now LUVOIR is the next big one.
But then... nothing.
It's 2026 now and I realized I haven't heard anything about LUVOIR in years.
Turns out I wasn't waiting for a delayed LUVOIR launch.
LUVOIR basically evolved into the Habitable Worlds Observatory (HWO)
I genuinely thought I'd eventually get to watch a giant telescope called LUVOIR launch after following it for a decade haha
Shit posting
I know this is a very random request, but I figured this would be the best place to ask.
I'm really interested in seeing a video of someone handling a vial of dimethylmercury. It's a strange combination of chemistry curiosity and the unsettling feeling of watching someone work with one of the most dangerous substances ever used in a laboratory.
Does anyone know if such a video exists, or has it simply never been publicly recorded?
I came across a YouTube Short where someone charges a 450 V, 560 µF electrolytic capacitor using one of those small handheld high-voltage generators (the type commonly advertised as producing around 10-20 kV).
From what I can see in the video:
→ The capacitor is a 450 V, 560 µF electrolytic.
→ The HV generator is connected directly to the capacitor.
→ The capacitor charges very slowly (it takes several seconds).
→ After charging, the measured voltage across the capacitor is about 441.7 V.
→ The capacitor doesn't vent, explode, or appear damaged.
My understanding is:
→ A capacitor's voltage rating is the maximum continuous voltage that should be applied across it.
→ If the applied voltage exceeds that rating (especially by a large margin), the dielectric should eventually break down, causing damage or failure.
→ Since the HV source is advertised as 10-20 kV, I would have expected the capacitor to fail long before reaching such voltages.
What I'm struggling to understand is:
→ Why was the capacitor apparently able to charge safely to only ~442 V instead of being exposed to the full advertised 10-20 kV?
→ Why did charging take several seconds if the source is supposedly producing such a high voltage?
→ Is the explanation simply that these small HV generators have an extremely high internal resistance/current limit, causing the output voltage to collapse under load?
→ Do these modules effectively stop increasing the capacitor voltage once leakage and source characteristics reach equilibrium, or is there another mechanism involved?
I'm mainly trying to reconcile the advertised 10-20 kV output with the fact that the capacitor ended up at only 441.7 V without failing.
Am I misunderstanding how these inexpensive high-volta generators behave under load, or is there another explanation?
I got it with my YL Laser 303.
It charges well for now,
But I'm scared if I someday forgot to take it out of the charger it may overcharge and explode
Hi everyone,
I recently turned 18 and am currently in my final year of high school. I do not have any source of income at the moment.
Electronics has been a passion of mine for years, especially designing and building circuits. Over the past few weeks, I saved up and convinced my parents to let me buy around ₹700 worth of components for learning and experimenting. I am very grateful that they agreed to that.
Unfortunately, I realized that I am still missing one essential part to complete my current project: three LM370 voltage regulator ICs, which cost ₹134 (approximately US$1.60).
I cannot ask my parents for more money because they have already spent more than they were comfortable with on the earlier components, and I understand their decision.
I know this is not a necessity compared to many other requests here, and I completely understand if people choose to prioritize others. However, if anyone is willing to help me with ₹134 (approximately US$1.60) so I can order the remaining ICs and finish my project, I would be incredibly grateful.
Financial situation:
- Final-year high school student
- No income
- Not receiving any government assistance or benefits
If anyone is able to help, I can only accept an Amazon.in gift card, as I plan to use it to purchase the components directly from Amazon India.
Thank you for taking the time to read my post, whether or not you are able to help.
I salvaged an old DVD player and have progressively disassembled the optical pickup assembly (WTP-AD01)
I've attached four photos showing the stages of disassembly, with the last two photos showing the front and back of the optical block.
I suspect the laser diode is still inside the remaining optical assembly, but I'm hesitant to disassemble it further in case I damage the diode or any of the optics.
Can anyone identify where the laser diode is located in this pickup and whether it can be accessed without destroying the assembly?
My goal is mainly to understand the construction of the optical pickup and locate the diode.
Any help or pointers would be appreciated.
So I know attendance dosen't matter,
But till today (25th Jun 2026) I have gone to school literally only ONCE.
(Private school)
Why is it showing 0 current?
​
I thought those 5 (215ohm each) resistors are in parallel
The battery shows 8.5V
So total current should be 197mA which is distributed across each Resistor
These are the first two purchases I’m making for my EE pathway. What else can I do with them besides what I’ve already planned (like verifying Ohm’s law, Wheatstone bridge, cube resistor, and experimenting with a multimeter to measure and verify series/parallel current and voltage division)?
Is this correct intuition for the flow of current?
I also thought of this abstractly rather than the typical water analogy
I can just think of those ideal wires as resistors BUT with 0 Resistance
Therefore by the parallel current distribution law, 100% of the current must flow through them and 0% through the rest that are in parallel to it
I was thinking about a conceptual issue in basic circuit theory and wanted to clarify the meaning of “equipotential” more rigorously.
Consider two points A and B connected by an ideal wire in a battery-resistor DC circuit. We often say the wire is equipotential, meaning V ᴀ = V ʙ , so Δ V = 0 along the wire segment.
My confusion arises from the following reasoning:
If V ᴀ = V ʙ , then ∇ V = 0 along the wire, so E = 0. Using J = σ E, it seems like current density inside that segment should be zero.
But in a steady-state circuit, we know current is nonzero everywhere in the loop, including through that wire segment. This leads to an apparent contradiction:
- If the wire is truly equipotential, does that imply no current flows between A and B?
- If current does flow, does that mean the wire cannot be strictly equipotential?
- And if current exists while E = 0, how is continuity maintained without any “jump” in current at the resistor?
I’m trying to understand precisely how “equipotential wire” is defined without conflicting with current continuity.