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Can someone help me with physics?
If a CD laser has a power output of 0.30 watts, then how many quanta of laser light does the laser emit each second? A watt is a joule per second (J/s).
1 Answer
- Anonymous5 months ago
You need the wavelength. Are you given the value?
Old CD players use lasers with wavelength = 780 nm.
DVD players use wavelength = 650 nm.
Blu-ray uses 405 nm.
I’ll go with 780 nm, but change it if you need to.
Energy in 1 photon (quantum) E = hc/λ
= 6.63*10^-34 * 3*10^8 / (780*10^-9)
= 2.55*10^-19 J
Remember a power of 0.30W means 0.30 J each second.
No. of photons/second = P/E
= 0.30/(2.55*10^-19)
= 1.2*10^18