1. The photoelectric effect for a certain alloy has a threshold frequency of 5.8
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Question
1. The photoelectric effect for a certain alloy has a threshold frequency of 5.80 x 1014 Hz. For light of this frequency, find the energy of one mole of photons (in kJ).
2. An electron in the 8th energy level of the H atom drops to the 3th energy level. In other words an electron in an excited state drops to a less excited state. What is the energy (in J) of the emitted photon? The energy of an electron in the nth level is
3.The absorption spectra of ions have been used to identify the presence of the elements in the atmospheres of the sun and other stars. What is the energy of a photon (in J) that is absorbed by He+ ions, when an electron is excited from the Bohr orbit with n = 1 to the n = 8 state? The energy of an electron in the nth level is
where B = 2.18 x 10-18 J and Z = charge on nucleus (number of protons).
En = - Bn2 = - 2.18 x 10-18 J/n2Explanation / Answer
I base my calculations on the assumption that you typed 7.00 x 1014 Hz for frequency but you probably meant 7.00 x 10^14 Hz.
E = nhf
n is the number of moles (one)
h is the Planck's constant (6.63 x 10^-34)
f is the frequency (7.00 x 10^14)
Hence, multiplying them together, energy E = 4.641 x 10 ^ -19 joules
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