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  1. J

    General Thoughts: Physics

    with the projectile I got something insanely small, something x 10-8 seconds... With the one where you had to find the magnetic field strength, didn't you need to know the charge on proton? I assumed it was equal to electron charge.
  2. J

    T1 and T2

    I think T1 is the time it takes for the nuclei to transfer the energy to the surrounding molecules, and T2 is the time it takes for the nuclei to revert to out-of-phase precession through the exchange of energy. Watery tissue takes longer in both, as they move faster than large molecules and...
  3. J

    Could someone give me an overview of Hertz's experiment?

    When the spark jumped across the transmitter, a spark also jumped across the detector loop (just a plain loop of metal). He 'accidentally' discovered the photoelectric effect when he started firing UV light at the detector and found that the spark was stronger. As gabgab said, the EMR from...
  4. J

    exam question predictions 2009

    there's too many questions to guess properly... there'll be something to do with most things I agree with Aerath :D
  5. J

    Relativity

    I think dumbledore is correct t0 is the time on the ship, so you do it like him Another way of thinking about it is the ship thinks the length has contracted, either way you're multiplying by sqrt(1-v^2/c^2)
  6. J

    Black body radiation

    The temperature in the black body (which determined the energy of the radiation coming out) would peak at a point where the energy coming out corresponded to the particular photon energy, hence a peak at a particular frequency in each temperature. At higher frequencies, the energy in a photon...
  7. J

    Induction Motors

    As anom1ly said, there's 3 sets of electromagnet coils in a circle as a stator (six coils altogether). They turn one pair on, then off, then the next pair on, and so on until they have a 'rotating' magnetic field. The rotor can be a squirrel cage structure mounted inside. The rotation is...
  8. J

    Michelson Morley experiment

    Yeah when they rotate it 90 degrees they're 'changing' the relative direction of both light rays relative to the ether. They predicted them to go at different velocities because of the constant ether wind direction, and then produce a different interference pattern. That's what I heard :D But...
  9. J

    Trial Q on M&G i can't do

    Yeah. 0.01T x 0.04m x 10A (BIl) gives you their answer
  10. J

    Televisions

    "Why is a magnetic field preferred in television sets to deflect electrons when compared to a uniform electric field?" I really have no idea.. has it got anything to do with the way they deflect, where a magnetic field causes a circular path whereas an electric field just creates an arc? Thanks ;)
  11. J

    Length Contraction Question

    So if the light clock is moving horizontally, why does it contract? The only idea I got is that the clock moves to meet the reflected beam, making it take a shorter amount of time, and since the speed of light is constant, length must contract to compensate. But then, wouldn't the light beam...
  12. J

    Length Contraction Question

    Heya Could someone please explain the length contraction thought experiment? So the one in my textbook says that a light clock in a train operates horizontally, but yeh I don't get how that shows length contraction Thanks :D
  13. J

    Does back EMF only occur in DC motors?

    Yeah, the back emf produced is directly proportional to the change in flux according to Faraday's law. When the load increases, the speed of the motor reduces. The change in flux reduces, and so the back emf is less. The supply voltage remains constant, and as Nuendo said, this makes the net...
  14. J

    Torque on a Coil

    Yeh for clarification the Ө in F=BIl sin Ө is angle between current and magnetic field, Ө in BIA cos Ө is angle between the coil and the magnetic field
  15. J

    revising

    3) Okk what we do is choose projection point as the origin, and this is easier because it's only got one dimension. What we're told to solve is the t and v at s = -50 then. So we use -50 = ut - 0.5at2, and solving for t we get t = 6.56 or -30.5. Since the origin is 50m above the ground, we...
  16. J

    Estimate Raw Mark

    Hopefully 90 Hopefully equal to or above danz90 :P
  17. J

    Section I: Multiple Choice

    Oh ye proringz Did yer get the same answers as me when you checked :P
  18. J

    Who is expecting to get spanked by chem?

    Got spanked by a couple of questions. <3 all those calculations!! yippe
  19. J

    Section I: Short Answers

    Yeah, for the location I wrote about farms xD EDIT: Well, I'm outta here, exam's over! :D
  20. J

    Section I: Short Answers

    I think I totally failed it... my friends wrote how agricultural activities, boating, <S>swimming</S>, and all that was prohibited, I wrote about what available equipment they have (sand or membrane filters) and what effects the water, for them to decide what they gotta do about it
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