Question

Calculate the energy in Joules for a photon with a wavelength of
400 nm. Report your answer to 4 significant figures using
scientific notation. (Ex: 1.345E-17 should be entered for 1.345 x
10^{-17})

Answer #1

That is: E = hf, where h is Planck's constant, equal to 6.625 *
10**-34 joule-sec.

The frequency is related to the wavelength (w) by: f = c/w, where c
is the speed

of light, 2.9979 * 10**8 meters per second. Put these formulas
together and we

obtain: E = hc/w

Since h and c are constant, their product hc is constant, 19.861 *
10**-26 J-m.

We are given w = 400 nanometers = 4.00 * 10**-7 meter.

So the energy E = hc/w = (19.861 * 10**-26 J-m) / (4.00 * 10**-7
m.)

E = 4.965 * 10**-19 joule to 4 significant figures

Calculate the difference in energy (in joules) between a
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λ
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λ
= 339 nm. Enter your answer in scientific
notation.

When copper is bombarded with high-energy electrons, X-rays are
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A Be3+ ion emitts a photon with a wavelength of 6.42
× 100 nm. If the energy of the initial state of the
Be3+ ion was -3.88 × 10(-18) J, calculate the
energy of the final state. Express answer in scientific
notation.

Calculate the energy, in joules, for a photon of 1024 nm
light.

When light of wavelength, 115 nm, impinges a photocathode that
has a binding energy of 2.59 eV, electrons are ejected. What is the
speed (in m/s) of the ejected electrons? h = 6.626 x 10–34J·s, c =
2.9979 x 108m/s, 1 eV = 1.602 x 10–19 J, NA= 6.022 x 1023mol–1, me
= 9.11 x 10–31 kg, KE = ½ mv2. Report your answer to three
significant figures. It might be easier to enter your answer in
scientific notation. So,...

(a) What is the energy in joules of an x-ray photon with
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J
(b) Convert the energy to electron volts.
keV
(c) If more penetrating x-rays are desired, should the wavelength
be increased or decreased?
increaseddecreased
(d) Should the frequency be increased or decreased?
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When an x-ray photon with λλ 0 = 0.58 nm is
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What is the energy (E) if the incident photon (in keV)? Use h =
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(keep 7 significant figures in your answer)
What is...

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Calculate the energy (in joules) of each photon that is emitted
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Calculate the energy of a photon, in J/mol, having wavelengths
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a) 400 nm and
b) 3.3 micrometers

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