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  1. page IB DP Topic 8 Energy production edited ... {car engine.PNG} Black body radiation from sci.esa.int and www.giangrandi.ch Task on Black…
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    {car engine.PNG}
    Black body radiation from sci.esa.int and www.giangrandi.ch
    Task on Black body temperature simulation
    Using the temperature slider, set the temperature to 3000 K (light bulb), 5700 K (Sun), and 8490 K (hot star).
    Use the zoom in and zoom out controls on the left side to adjust the y-axis as necessary.
    Compare the color of the object (the star-shaped object near the B G R color spots), the wavelength where the curve peaks, and the height of the curve's peak for all three temperatures.
    Black body simulation from phet.colorado.edu

    Stefan- Boltzmann law
    The thermal energy ratiated by a blackbody emitter per second per unit area is proportional to the fourth power of the absolute temperature.
    (view changes)
    3:58 am
  2. page IB DP Topic 8 Energy production edited ... Power emitted by an object is proportional to the surface area and the fourth power of the tem…
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    Power emitted by an object is proportional to the surface area and the fourth power of the temperature.
    {car engine.PNG}
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    body radiation and colour temperature from sci.esa.int and www.giangrandi.ch
    Stefan- Boltzmann law
    The thermal energy ratiated by a blackbody emitter per second per unit area is proportional to the fourth power of the absolute temperature.
    (view changes)
    3:41 am
  3. page IB DP Topic 8 Energy production edited ... Power emitted by an object is proportional to the surface area and the fourth power of the tem…
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    Power emitted by an object is proportional to the surface area and the fourth power of the temperature.
    {car engine.PNG}
    Black body radiation and colour temperature from www.giangrandi.ch
    Stefan- Boltzmann law
    The thermal energy ratiated by a blackbody emitter per second per unit area is proportional to the fourth power of the absolute temperature.
    (view changes)
    3:28 am
  4. page IB DP Topic 8 Energy production edited ... ·The mass m is thus m = ρV = ρAvt · Kinetic energy = (1/2) mv^2 = (1/2) ρAvt v^2 = (1/2) ρ Av…
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    ·The mass m is thus m = ρV = ρAvt
    · Kinetic energy = (1/2) mv^2 = (1/2) ρAvt v^2 = (1/2) ρ Av^3 t
    ...
    ½ (Aρv^3)
    PRACTICE: Since the air is still moving after passing through the rotor area, obviously not all of the kinetic energy can be used. The maximum theoretical efficiency of a wind turbine is about 60%. Given a turbine having a blade length of 12 m, a wind speed of 15 ms-1 and an efficiency of 45%, find the power output. The density of air, ρ is 1.2 kg m^-3
    SOLUTION:
    ...
    3) Molten iron 1810 K >>λ max = 1600nm
    4) Cosmic Background Radiation: 2725K >> λ max =
    {https://qph.ec.quoracdn.net/main-qimg-9e6676850d5024327cdb2302aedc6469}
    Planck Law -- Wolfram Diagram from scienceworld.wolfram.com

    Intensity
    The power per unit area that is received by the object. It's average value is about 1400 W/m^2
    (view changes)
    2:56 am

Monday, July 17

  1. page IB DP Atomic and Nuclear physics edited ... The Royal Institution Published on 8 Jun 2016 Breakthrough in Nuclear Fusion? - Prof. Dennis …
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    The Royal Institution Published on 8 Jun 2016
    Breakthrough in Nuclear Fusion? - Prof. Dennis Whyte MIT Club of Northern California Published on 25 Feb 2016
    Summary of atomic spectra
    atomic electrons can only exist in certain discrete energy levels.
    light is made up of photons.
    when electrons lose energy they give out light.
    when light is absorbed by an atom it gives energy to the electrons.
    >>when an electron changes from a high energy level to a low one, a photon of light is emitted. The electron can only exist in discrete energy levels.
    DE = hf
    DE : Change in energy
    h : Plank constant
    f : Photon frequency
    EXAMPLE 1: In an atom with electrons in two energy levels, calculate the wavelength that gives the rise to a photon when the change in energy is from the -4 eV to the - 10 eV.
    SOLUTION:
    DE = 6 eV = 6 x 1.6 x 10-19 = 9.6 x 10-19
    f = DE/h = ( 9.6 x 10-19 ) / ( 6.63 x 10-34 ) = 1.45 x 10-15 Hz
    c = f l
    l = ( 3 x 10 8 ) / ( 1.45 x 10-15 ) = 207 nm [UV light]

    (view changes)
    9:48 am

Saturday, July 1

  1. page IB DP Topic 5 Electricity and Magnetism edited ... {mit 1.PNG} {mit 2.PNG} {Force on current carrying conductors experiment.jpg} MIT Phys…
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    {mit 1.PNG}
    {mit 2.PNG}
    {Force on current carrying conductors experiment.jpg}
    MIT Physics Forces on a Current-Carrying Wire mittechtv published 8 Aug 2008
    MIT Physics Jumping Wire mittechtv published on 8 Aug 2008
    Force on current-carrying wire
    The magnetic force on a current carrying wire with the length L is ( L is the length of the wire in the region of the magnetic field.) :
    F = BIL sin q
    {Force onq is the angle between the current carrying conductors experiment.jpg}
    Force
    andd the direction of the magnetic field.
    The direction of Force
    on current carrying conductors can be found using Fleming's left hand rule.
    {Flemings left hand rule.jpg}
    Fleming's left hand rule for the relative directions of force, field and current
    EXAMPLE 2) State the diretion of the force on wire Z. The currents of X, Y and Z are equal magnitude. The directions of the currents are shown as
    {current carrrying wires XYZ.PNG}
    SOLUTION:
    X attracts Z and Y repels it. Y is closer to Z so the force it exerts is larger than wire X. Hence the force is to the right.

    Magnetic force and field
    ELECTRIC AND MAGNETIC FIELDS IN A COLLIDER - link to Starts with a Bang blog (Dec 2011)
    (view changes)
    10:39 pm
  2. page IB DP Topic 5 Electricity and Magnetism edited ... {Force on a charged particles.jpg} Force on a charged particles.jpg The magnetic force on a c…
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    {Force on a charged particles.jpg} Force on a charged particles.jpg
    The magnetic force on a current-carrying wire
    MIT{mit 1.PNG}
    {mit 2.PNG}
    MIT
    Physics Demo -- Forces on
    ...
    Wire mittechtv Uploaded onpublished 8 Aug 2008
    Force on current-carrying conductors experiment

    MIT Physics Demo -- Jumping Wire mittechtv Uploadedpublished on 8 Aug 2008
    Force on current-carrying wire
    F = BIL sin q

    {Force on current carrying conductors experiment.jpg}
    Force on current carrying conductors
    (view changes)
    10:25 pm
  3. file mit 2.PNG uploaded
    10:19 pm
  4. file mit 1.PNG uploaded
    10:19 pm

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