Energy of light is proportional to intensity. Energy is spread evenly over waterfront so each electron gradually gains enough to be emitted.
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What is Einstein's model of light?
Light travels as particle-like discrete packets of EM radiation and energy, which is transferred to electrons in 1-to-1 collisions.
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What are the ranges of kinetic energy for a photoelectron?
0 up to hf - (work function)
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What is stopping potential? What's the equation for it?
P.D. needed to stop fastest electrons. eVs=Ek(max)
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How do fluorescent tubes produce light?
They contain mercury vapour, initial high voltage accelerates free electrons which collide with atomic electrons, exciting Hg atoms, which deexcite to release UV photons.
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How does phosphorous coating convert UV to visible light?
P atoms absorb UV photons and their electrons get promoted to much higher energy levels; they cascade down to ground state, releasing visible light photons.
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What can absorption spectra show?
The wavelengths of light absorbed by a cool gas
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What can emission spectra show?
The wavelengths of light emitted by a warm gas
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What phenomena support wave theory? What phenomena support particle theory? (for light)
Wave theory: interference and diffraction. Particle theory: photoelectric effect.
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What is the equation for de Broglie wavelength?
λ = h/mv
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How does electron diffraction work?
Electrons are accelerated and then fired at atoms; they interact with the spaces between the atoms and hence their de Broglie wavelengths are diffracted.
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What part of EM spectrum has similar λ to electrons accelerated in vacuum tube?
X-ray`
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What is 1eV equal to?
Kinetic energy carried by electron after acceleration through a 1V p.d.
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Other cards in this set
Card 2
Front
What is Einstein's model of light?
Back
Light travels as particle-like discrete packets of EM radiation and energy, which is transferred to electrons in 1-to-1 collisions.
Card 3
Front
What are the ranges of kinetic energy for a photoelectron?
Back
Card 4
Front
What is stopping potential? What's the equation for it?
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