Answer
a) $3.73\times10^{-19}J$
b) $2.68\times10^{18}s^{-1}$
Work Step by Step
a) E=hν = hc/λ
h = $6.626\times10^{-34}Js$
c = $2.997925×10^{8}ms^{-1}$
λ = 533 nm = $533\times10^{-9}m$
E = $\frac{6.626\times10^{-34}Js\times2.997925×10^{8}ms^{-1}}{533\times10^{-9}m}$ = $3.73\times10^{-19}J$
b) Power of the laser = $1 Js^{-1}$
Energy of one photon = $3.73\times10^{-19}J$
Number of photons emitted = $\frac{1Js^{-1}}{3.73\times10^{-19}J}$ = $2.68\times10^{18}s^{-1}$