Friday, August 28, 2009

Day 9: The Photoelectric effect

The best was certainly saved for last. The experiment procedure itself was pretty straight forward but Dr Lombardi answered all our questions about this and touched on quantum mechanics, we could have asked him questions for hours but he eventually had to bring us back to the topi, which related to proving the dual nature of light. This was done by showing experimentally and with the use of equations that one photon can give its energy to 1 electron to free itself ( thereafter being refered to a photoelectron hence the photoelectron effect) , that intensity has no effect at all on the energy given to the electrons, ie sending a more intense wave of light say if there isn't a high enough frequency will not do anything.

Being last day of experiment we were all quite relaxed, we've been writing reports every day for the last 7 days we had just about mastered it ( shouldn't say that having not yet seen the marks for this experiment!)

Thebang leaning in for a closer look

I took a stroll around the campus after the exam the next day (Friday). This was a really cool feature

It's really pretty

Being here for these 2 weeks has been a great experience. Connecting with all the passionate scientists here and working on practical experiments was just awesome and I've left with my passion for science intensified.

Day 8: Physical Optics

This was a cool experiment, we got to play with different diffraction patterns , the one below is that of a blood cell that was inserted into a slide and placed over the slit. A Helium neon laser was shone through the slit creating a circular diffraction pattern. What you are meant to see is alternating dark and bright fringes but for the blood cell we only got to see 1 dark one, leaving us with dubious results.

We didn't get to do ourselves but got a demo from Dr Jones, who kept pulling electrons out of his pocket !

The diffraction pattern was really awesome to see. The electrons were thermionically emitted

Day 7: Force on a Current carrying conductor on a Magnetic Field

This was the worst of the experiments, because weighing these weights took elephant patience so i was really glad to be done with it. The theory in this case is alot more interesting than the practical

We finished a bit early so i took a stroll around the physics department where they also have their own library with some of the latest books and science magazines

We had time to kill before the observatory visit so I headed off to Leanes place for a quick chill and pizza Yums!

Visit to the observatory

UNISA by night, it was such a great evening

Thanks to Fanie we managed to get a guided tour of the observatory and a date with a 16" Celestron reflector telescope, courtesy of Prof Smuts who happily answered all our questions

Prof Smuts

the equipment, with Thebang awesomely capturing the pictures that follow through the viewfinder

Jupiter in all its glory with bonus moon in view, we actually suspected a 2nd moon as a speck over the actual diskAnd for the showstopper the moon itself. This was absolutely spectacular to see so close up

Happy people

What a great evening it was. Prof was awesome in describing so many things to us, we got to view some really ancient objects like the Omega Centauri globular cluster 12000 light years away !! We also got a good look at the Sombrero galaxythe oldest light that we got to see somet 50million light years away!!! It looks like a cigar because it was on its side , we also got to see some planetary nebula and the Jewel box and Alpha Centauri

Monday, August 24, 2009

Day 6: Charged Particle in a Uniform Magnetic Field

Day 6: Another cool experiment coming up. Out instructor (damn didn't write his name down!) should have received a prize for the brilliant explanation of the theory. It was outstanding
And here we have it, a set of Helmholtz coils, that will generate a uniform magnetic field to be able to watch the actual motions of electrons through this magnetic field. thats right actual electrons

Look closely
And....tadaaaa! There is your electron beam. Whats happening is that the electrons radiated from the heated metal resistor (thermionic emission) where accelerated into the plate and through into the glass sphere ( this happened because we applied a potential difference between the resistor and the plate, pushing the electrons in that direction. Once in the glass sphere, the electrons collide with the atoms inside the sphere, knocking some of their electrons into an excited state. When the excited electrons fall back into their stable orbits they emit visible light, giving away their position and revealing the path!

This is madness you ask? No this is UNISA!!

Observatory visit tomorrow witha 14" telescope!

Friday, August 21, 2009

Day 5: Electrical Measurements

Good morning Joburg! Friday and looking and feeling frazzled, last day of the week so bring it on!

Thank god its Friday. Don't know how much more of this pace a person can handle. Today was on Electrical measurements hence this picture which was taken out of the Halliday text book of a bee full of pollen. The pollen jumps onto the bee then away again, this has to do with electric fields would you believe!

Prof Lekale took us today, really nice and helpful. Our equipment was quite faulty so we didn't get to do the 2 parts of the experment ( one with resistor and one with a diode) to investigate ohmic and non ohmic behaviour. Cool experiment , I enjoyed doing the report , maybe because I wasn't so pressured for time. Also its only when you have to write the report you have to really understand the topic

Because we finished a bit early, me and some of the guys headed off to find the library, boasted as the 2nd biggest in the whole of Africa. Through a shortcut route is an area where they shred tons and tons of paper from tutorials etc and send it away on a recylcing truck

From the bottom floor of the library, 5 floors above full to the brim of books.

Carlson is a teacher ( there are quite a few at this course), we walked around aimlessly for a bit looking for the science section straight away. eventually we figured out the system

Here's mike checking out books on galaxies and black holes. He's also portuguese and a pilot who flies to some intersting places

There are So many books and some really old ones

This was on the back of a biology book and i had to take a pic as this monkey was so cute!

Ok thats its for this week, its been an awesome experience so far! Might do some edits on the weekend and lay this blog out better ( haven't touched the format). Off to do what one does when in Joburg...catch up with friends and family!

Day 4: Simple Harmonic Motion

Meet Yanik, one of the honours students giving us the lecture for today. Cool guy from Cameroon with a cool french accent. Here explaining the pendulum situation, with his model made from recycled goods. This pendulum later went missing!

Our workstations ( nope, no internet, its password protected ) Ok well just as well this experiment was LONG. Not difficult but really long. I really enjoyed doing it with the computer simulation. YOu get the measurements really accurate.
No food allowed to be eating in the class but you sneak one in when you get a chance!

Paying attention!