Question

Suppose you have a 10 watt fluorescent light bulb. If this light bulb is 6 % efficient in turning electricity into light, then how many photons are being emitted per second? Assume that average energy of all the photons emitted is 550 nm, thus you can treat all the photons as having the same energy as a 550 nm photon. Lastly, 1 watt = 1J/s

this is my answer
1.66E17
can you please tell me if i did it right

thank you

Answer 1

I have 1.66E18.
10 watt bulb @ 6% = 10*0.06 = 0.6 watt = 0.6 J/s. (I suspect we differ here.)

I used 6.626E-34 for h.
I used 3E8 for c.
I used 550E-9 for the wavelength.
This gave E = 3.61E-19
Then 0.6 J x 1 photon/3.61E-19 J =