Wikipedia
Search Wikipedia:

Latest topics
August 2017
MonTueWedThuFriSatSun
 123456
78910111213
14151617181920
21222324252627
28293031   

Calendar Calendar

Free Hit Counter

How many photons per second does the laser emit?

View previous topic View next topic Go down

How many photons per second does the laser emit?

Post  pplantblues on Sat Nov 22, 2008 2:39 pm

The power of a red laser (lambda=630 nm) is 3.5 watts (abbreviated W, where 1 W= 1 J/s)=
avatar
pplantblues

Posts : 109
Join date : 2008-11-14

View user profile

Back to top Go down

Re: How many photons per second does the laser emit?

Post  funion987 on Sat Nov 22, 2008 2:57 pm

I'm, not 100% sure this is right, but this is how I would solve it.

First, figure out the energy that one photon of red (630 nm) light has using Planck's equation.

E= hν

Energy (in joules)= Planck's constant (6.63 x 10-34) x frequency (in meters)

E= 6.63 x 10-34(630 x 10-9 m)

E= 4.18 x 10-40 J
This is the energy in 1 photon of 630 nm light.

Since the problem gives us that the energy is 3.5 W or 3.5 J/s, we need to find out how many photons with the energy above we would need to produce 3.5 J. SO we divide:

3.5/(4.18 x 10-40) = 8.37 x 1039 photons
avatar
funion987
Administrator

Posts : 146
Join date : 2008-11-09

View user profile http://chemistry.forumotion.com

Back to top Go down

Re: How many photons per second does the laser emit?

Post  pplantblues on Sat Nov 22, 2008 3:12 pm

This is what I got for an answer:
E=hc/landa=(6.626x10^-34 J/s)(3.00x10^8 m/s)/6.3x10^-7 m= 3.15x10^-19J
630nm x (10^-9/1 nm)=6.3 x 10^7 m
Since 1 W= 1 J/s
3.50 watts= 3.5 J/s
So 3.5 J/s / 3.15 x 10^-19= 1.11 x 10^-19 photons/s

Thanks for trying.
avatar
pplantblues

Posts : 109
Join date : 2008-11-14

View user profile

Back to top Go down

Re: How many photons per second does the laser emit?

Post  funion987 on Sat Nov 22, 2008 3:20 pm

You know what, I totally screwed that one up. Maybe it's best if I don't answer if I don'y know. Sorry. Embarassed
avatar
funion987
Administrator

Posts : 146
Join date : 2008-11-09

View user profile http://chemistry.forumotion.com

Back to top Go down

Re: How many photons per second does the laser emit?

Post  pplantblues on Sat Nov 22, 2008 3:29 pm

Don't worry about it ! You still rock
avatar
pplantblues

Posts : 109
Join date : 2008-11-14

View user profile

Back to top Go down

Re: How many photons per second does the laser emit?

Post  Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum