Answer
(a) $E = 3.70\times 10^{-7}~eV$
(b) $8.45\times 10^{29}$ photons are emitted per second.
Work Step by Step
We can find the energy of each photon:
$E = hf$
$E = (6.626\times 10^{-34}~J~s)(89.3\times 10^6~s^{-1})$
$E = (5.917\times 10^{-26}~J)(\frac{1~eV}{1.6\times 10^{-19}~J})$
$E = 3.70\times 10^{-7}~eV$
(b) We can find the number of photons per second that are emitted:
$\frac{P~t}{E} = \frac{(50.0\times 10^3~W)(1~s)}{5.917\times 10^{-26}~J} = 8.45\times 10^{29}$
$8.45\times 10^{29}$ photons are emitted per second.
