Answer:
C. 6.76 x 10^18 photons
Explanation:
First, we need to find the energy falling on 1 cm² in 1 minute. It is given to be:
Energy = E = 0.698 cal
Converting it into Joules:
E = (0.698 Cal)(4.184 J/1 Cal)
E = 2.92 J
Now, for the number pf photons, we know that this energy from sun is given by the formula:
E = nhυ
where,
h = Plank's Constant = 6.625 x 10^-34 J.s
n = number of photons
υ = frequency of wave
But,
υ = c/λ
where,
c = speed of light = 3 x 10^8 m/s
λ = wavelength = 460 nm = 460 x 10^-9 m
Therefore,
E = nhc/λ
n = Eλ/hc
n = (2.92 J)(460 x 10^-9 m)/(6.625 x 10^-34 J.s)(3 x 10^8 m/s)
n = 6.76 x 10^18