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Fusion is the process by which the sun produces energy. One experimental techniq

ID: 1793292 • Letter: F

Question

Fusion is the process by which the sun produces energy. One experimental technique for creating controlled fusion utilizes a solid-state laser that emits a wavelength of 1190 nm and can produce a power of 1.00 × 1014 W for a pulse duration of 1.10 × 10-11 s. In contrast, the helium/neon laser used at the checkout counter in a bar-code scanner emits a wavelength of 635 nm and produces a power of about 1.00 × 10-3 W. How long (in days) would the helium/neon laser have to operate to produce the same number of photons that the solid-state laser produces in 1.10 × 10-11 s?

Explanation / Answer

Solid state Laser :

energy of 1 photon = h c / lambda = (6.626 * 10^-34) (3 * 10^8) / (1190 * 10^-9)

= 1.67 * 10^-19 J


P = E / t

E = 1100 J

no of photons = 6.587 * 10^21

total energy = (6.587 * 10^21) (6.626 * 10^-34 * 3 * 10^8) / (635 * 10^-9)

= 2062 J


Power = energy / time

(1.00 * 10^-3) = 2062 /t

t =2062003.88 sec Or 572.78 hrs Or 23.87 days