TSR Physics Society

Hello

Can someone please describe and explain the differences between the interference pattern from double-slit and diffraction grating?

Thank you in advance.

Differences:

- the interference in a diffraction grating causes more minimums in comparison to double slit, see here
- the diffraction grating has many different maximums, the one which have small amplitudes and the one which have great amplitudes (see the link).
- the double slit has three maximums with equal amplitudes (see the link).
- That is why the diffraction grating has differences in brightness, while the double slit has three equal brightnesses (see the link).

Thanks!

The thing I don't get is why double slit has equal amplitudes whilst single slit has varying maxima and minima?

(...)I don't know for sure but I'd wager that all uv wavelengths can do is kick out valence electrons. (...)

(...)Photo ionisation isn't particularly common though. The photons are really weakly ionising so you need a big dose of them to get the same damage as an alpha particle or beta plus or minus etc. Having said that, it's still pretty dangerous. There was this one guy (this is a well known story but I can't remember his name) back when the imaging use of X-rays was discovered who worked in a photography shop. They had an X-ray producing thing (most likely something like a cathode ray tube) and used it to amaze customers by getting the poor sod I mentioned above to show off the bones in his hands on photographic film (I can't remember the name of the film they use but it's 3am so meh). The guy had to quit the job 4 days in because his hands had become swollen bright red blobs of dermatitis and the skin was peeling off them (if you're eating while reading this I'm sorry!).(...)

Hello, me after a while!

I have heard that physicists have discovered gravitational waves. The one which were supposed by Einstein, but would never be discovered after his estimation. Do you know more about that?

The full paper is up online if you want to see the graphs - I expect it's not behind a paywall because of government funding.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.061102

the list of authors is crazy... and afaik they have to pick just 3 of them for the Nobel

Have taken a closer look in the last week to the gravitational waves. Just to understand the meaning of these ones:

If two neutron stars or two black holes are circling each other, a distortion of space-time comes into being what emits gravitational waves which are causing a length variation of objects in the range of those waves. That is to say the objects are getting shorter or longer, even if its a tiny bit. And this length of variation was proved by high sensitive lasers which were really changed in their length a little tiny bit.

Yeah, that is right. three people at the maximum are just able to win a nobel prize in physics in a year, not only in physics, but also in another categories.

Hello guys. For someone who has little physics knowledge (A-level) and is eager to learn more, would you say the Feynman lectures are a good start?

Yeah

Feynman was a brilliant teacher. Definitely worth your time.

Lol thought I was never going to get an answer. Cheers mate, that's on my 'after exams to-do-list'.

It's a long read haha.

You can get all volumes free from the Caltech website. Electromagnetism is one of the most beautiful topics in Physics (Vol 2?).