- #1
map19
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Publicity often says that a new telescope can detect a candle across the Atlantic, etc.
Well, a candlepower is defined as 1/683 Watts at 540 X 10^9Hz.
This gives photon energy at 2.2 eV.
One candlepower produces 4.2 x 10^15 photons/s radiated isotropically.
At 3,000km the area of the sphere is about 10^14m^2
So the photon density at the telescope is 4.2 x 10^15/10^14 or about 4 photons per sq meter per second.
Two things to note:
The associated electromagnetic field would be very small, but not zero.
A second is a long time in quantum matters.
My questions are: How do you demonstrate the area covered by a photon at the telescope mirror ?
How long is the photon wavetrain ?
(I can’t believe I’m asking this) does the field collapse to the photon particle ?
Is this like the photoelectric effect where a classical calc shows that 10 minutes or so would be required to dislodge the electron, where in fact it occurs in about 10^-9s.
Well, a candlepower is defined as 1/683 Watts at 540 X 10^9Hz.
This gives photon energy at 2.2 eV.
One candlepower produces 4.2 x 10^15 photons/s radiated isotropically.
At 3,000km the area of the sphere is about 10^14m^2
So the photon density at the telescope is 4.2 x 10^15/10^14 or about 4 photons per sq meter per second.
Two things to note:
The associated electromagnetic field would be very small, but not zero.
A second is a long time in quantum matters.
My questions are: How do you demonstrate the area covered by a photon at the telescope mirror ?
How long is the photon wavetrain ?
(I can’t believe I’m asking this) does the field collapse to the photon particle ?
Is this like the photoelectric effect where a classical calc shows that 10 minutes or so would be required to dislodge the electron, where in fact it occurs in about 10^-9s.