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Home Q & A Board Science-Related Homework Help Physics
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Marcosiu Marcosiu
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9 years ago
1,How many visible photons would be needed to have enough energy to lift a 0.8 newton weight through 0.2 meter? (Assume a visible photon has a frequency of 5 ✕ 1014 Hz.)
= ? photons

2,Making estimates. The human eye can detect as few as 9920 photons per second entering the pupil. About how much energy is this, per second? (Assume the photons have a wavelength of 300 nm.)
= ? J

3,If you triple a proton's speed, how does this affect its wavelength?
λnew / λold =   ?
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#1
Educator
9 years ago
Quote from: Marcosiu (9 years ago)
1,How many visible photons would be needed to have enough energy to lift a 0.8 newton weight through 0.2 meter? (Assume a visible photon has a frequency of 5 ✕ 1014 Hz.)
= ? photons

You need 0.16 joules.

And each visible photon has an energy of around 2 or 3 electron volts.

You do the sums, or use the equation E = hf and f = c/wavelength. I'm not going to do all your homework for you.
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