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What causes light to become brighter?

  1. Jun 28, 2011 #1
    Why and how does light get brighter as you increase a light bulbs voltage?
     
  2. jcsd
  3. Jun 28, 2011 #2

    phinds

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    for a given frequency, brightness is just a measure of the number of photons. When you increase the current in a bulb wire it gets hotter and emits more photon. When you increase the voltage, you increase the current.

    SO .... more voltage => more current => more photons => brighter
     
  4. Jun 28, 2011 #3
    Ahh right. So when current passes through and light bulb and heats it up, is the light produced when the electrons in the filament gain energy so they go up a shell then since there's an empty space, it goes back down into that space. So then it's releases that energy as a photon? So, by taking into account what you said, basically, as the temperature increases, from more current, the filament gets hotter, so more electrons are moving?
     
  5. Jun 28, 2011 #4

    Drakkith

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    That is pretty much correct. The more current through the filament the more it heats up. The more it heats up the more light it produces.
     
  6. Jun 28, 2011 #5
    Great! Only things is, I am watching this program about Quantum Mechanics and the guy on it said that photons of different frequencies of light have different amounts of energies. He was talking about the photoelectric effect. Is this true? Because I though than every photon has the same amount of energy, but the energy only increases because its frequency increases. So more photons pass a certain point in a period of time. So there is more energy but the amount of energy in each photon is the same.
     
  7. Jun 28, 2011 #6

    Drakkith

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    Each photon has a specific amount of energy that is determined by its wavelength or frequency. Red light has less energy than blue light because its wavelength is longer. Higher energy light isn't brighter though. Brightness is purely due to the amount of photons entering your eye.
     
  8. Jun 28, 2011 #7
    Oh, so every photon of a certain frequency has the same amount of energy but the energy of photons of different wavelengths or frequency. Are photons all the same size?
     
  9. Jun 28, 2011 #8

    Drakkith

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    I don't believe photons have a volume associated with them. IE they don't have a size. They are a wave of electric and magnetic fields that propegates through space.
     
  10. Jun 28, 2011 #9
    How does light actually travel? I know it travels in waves, do the photons follow that the shape of the wave? Also, why do they travel like that? Why not it a straight, direct line?
     
  11. Jun 28, 2011 #10

    Drakkith

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    The waves ARE the photon. The electric and magnetic field oscillate back and forth perpendicular to each other.
    The depictions of all particles of little balls is incorrect. To understand the reality you would need to read up on Quantum Mechanics.
     
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