electromagnetic radiation with a wavelength of 531 nm appears as green light to the human light. The energy of one photon of this light is 3.14 x 10^ -19. thus, a laser that emits 1.3 x 10^ -2 J of energy in a pulse of light at this wavelength produces _________ photons in each pulse?
can someone please help me work this problem out?
a. 9.2 e(-24)
b. 3.5e (16)
C. 2.9 e(-17)
d. 1.8 e (19)
e. 6.5 e (13)
2007-09-29 09:23:17 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Physics
hi,
the ans is b.
just divide the total energy in a pulse of light by the energy of one photon that gives u the no. of photons.
(thats valid only if the energies have the same unit!!)
Hope that helps!!!
2007-09-29 09:36:15 · answer #1 · answered by Turquoise 2 · 0⤊ 0⤋
Simply divide 1.3 x 10^-2 by 3.74 x 10^-19
You have typo'd in your question. That should be 3.74 instead of 3.14.
Since E = h*c/lambdha
Thus the energy of one photon of light at 531 nm:
E = (6.63*10^-34)*(3*10^8)/(531*10^-9)
= 3.74*10^-19 J
Number of photons = Energy of Laser/Energy of one photon
= 1.3*10^-2 / 3.74*10^-19
= 3.5*10^16
So answer is B.
2007-09-29 16:28:38 · answer #2 · answered by bassdude_46 2 · 1⤊ 0⤋
It's the total energy divided by the energy per photon. I get
4.14x10^16 photons so I'd guess the answer is probably (b).
Doug
2007-09-29 16:44:55 · answer #3 · answered by doug_donaghue 7 · 0⤊ 0⤋