1B.9 (7th edition)

$E=hv$

hannahdaijo_4H
Posts: 48
Joined: Fri Sep 28, 2018 12:27 am

1B.9 (7th edition)

The textbook says, "...the intensity of radiation is an indication of the number of photons present, whereas E = hv is a measure of the energy of each individual photon." But in 1B. 9 (of the 7th edition), the question asks for the number of photons that can be generated and how many moles of photons are emitted in the given time interval. What denotes intensity if E = hv indicates energy? Or are they the same in practice? And can someone please explain the steps for how to get the answer to the second part of the problem ?

juliefilice 4A
Posts: 31
Joined: Fri Sep 28, 2018 12:27 am

Re: 1B.9 (7th edition)

Energy and intensity aren't the same in practice. You first find the total energy (32W*1J/s*2s=64J), then find the energy per photon using E=hc/lambda. Calculate the number of photons by dividing the total energy by the energy/photon, then convert this number to moles by dividing by Avogadro's number for part 2.