Fun With Physics At Independent Learning Lab In SRC...
went with Henry to try out the stuff and looks like the interest in Physics among people is lacking, cos when i went there, no one else were there, only Dr Lim and it was kinda pathetic, though one person did come later. Aiyo, Dr Lim was kinda happy to see us and happily explained every set up to us. As it is an independent learning lab, we are supposed to think about some phenomenon ourselves (some of which we haven't learnt cos we haven't touched magnetism). So first think i asked for was to take pictures, no not enough i took videos too. And first thing he asked was whether we are in J1 or J2, lol.
These are VERY simple stuff... Though i explain so much...in case ppl have forgotten wat hey learn in upper sec...
because i love sooooooo much to explain Physics stuff, when it comes to descriptive questions in examinations, (esp on electricity) well...i've definitely got enough practice and will certainly enjoy the paper! =)
ELECTRON GUN
First is the electron gun, as the electron beam from the gun cannot be seen (obvious) a flourescent screen has to be placed in front of the beam so that the electrons will interact with the screen and dunno what light photon thingy then you will see a bright dot which forms, remember Cathode Ray Osciloscope? O level stuff. so look at the picture below, at its left is the glass ball thing in which an electron gun is shooting electrons, the bright dot u see on the white screen is actually the light that is formed when electron touches the fluorescent screen, to the picture's right is the thing used to control the voltage supplied to the beam, click to enlarge pic, it says 1kV maximum and we were using 1.12kV, well...
below is a video of me explaining the deflection of the beam when a magnet is placed near it using Fleming's Left Hand Rule, so i was talking about which finger represents wat, if u can reacall, thumb is force on the beam, middle finger is current, index finger is magnetic field (pointing from north pole to south pole). so the pole of a magnet can be determined by looking at the direction in which the current is deflected, as u know current is flowing opposite to the direct of the electron flow n the beam, so i pointed my middle finger inwards as electrons are being shot outwards, ya then when i place the north pole of the magnet at the side of the beam, it is deflected upwards (upward force as indicated by the thumb), indicating the north pole is facing the beam. (sorry if my voice is not clear in video, cos i didn't want to talk loudly and disturb Dr Lim, and put on earphones if u can't hear)
enjoy...
SOLENOID - ELECTROMAGNETISM
below is solenoid that i came across, the solenoid is connected to a multimeter (left) to show that a current is indeed flowing in it when the switch is on.
basically i put a steel ruler in outside the solenoid and when i on it it immediately is attracted into the solenoid, and after that magnetism is induced in the ruler and the effects are kinda permanent cos the ruler is made of STEEL not IRON. anyway the multimeter shows that there is a current flowing thru it. so when i take it out it can attract paper clips, as i always wanted to induce magnetism on my own stainless steel scissors, and once i succeeded in inducing a very weak magnet by myself at home using the stroking technique, but now i just put into the solenoid and switch it on and poof, my scissors magnetism is now kinda strong. again enjoy the video below!
another thingy which can generate voltages of different waves (the wave like a sine curve, square waves and even triangular waves) in this case i am generating a square like wave which is measured on the multimeter (click to enlarge and see the wave on the multimeter's screen) (picture below)
INDUCING EMF IN A SOLENOID BUT MOVING A MAGNET THROUGH IT
again below is a picture of a solenoid (right), when i move a strong magnet thru it, EMF is induced and it is measured by a multimeter set to voltage mode (left of pic), so u can see waves forming on the multimeter, in a voltage against time graph.
recall that the EMF induced is NOT fixed, cos the EMF is highest when my magnet is pushed most in, also the voltage measured is negative and positive since i am moving magnet up and down, so waves are formed on multimeter at voltage against time graph, so below are 2 videos of me doing it, sorry cos dunno how to scale the multimeter, the waves are tall but damn close apart. basically when i dun put a magnet thru it or when the magnet is still, no EMF is induce cos no change in magnetic flux, then will see a straight line graph at y=0...haha! meaning 0V thruout. again i would advise u to put on earphones to listen to me cos i was talking real softly.
got 2 videos cos i felt one was not enough LOL.
posted by Damian @ 11:15 PM;
