Answer:
The value is  [tex]N = 2.69 *10^{26} \ photons[/tex]
Explanation:
From the question we are told that
  The power is  [tex]P = 510 \ W[/tex] Â
  The wavelength is  [tex]\lambda = 10.5 \ cm = 0.105 \ m[/tex]
 Â
Gnerally the number of photon produced is mathematically represented as
       [tex]N = \frac{P * \lambda }{ h * c }[/tex]
Here  [tex]h[/tex] is the Planck's constant with a value  [tex]h = 6.62607015 * 10^{-34} J \cdot s[/tex]
     c is the speed of light with value  [tex]c = 3.0*10^{8 } \ m/s[/tex]
So Â
       [tex]N = \frac{ 510 * 0.105 }{ 6.62607015 * 10^{-34} * 3.0 *10^{8} }[/tex]
=> Â Â Â Â Â [tex]N = 2.69 *10^{26} \ photons[/tex]