Question

The blue color of the sky results from the scattering of sunlight by air molecules. The blue light has a frequency of about 7.5 x 1014 Hz. What is the energy associated with this frequency?

Answer 1

Answer: The energy associated with blue light is $49.65\times 10^{-20}J$

Explanation:

To calculate the energy of the light for a given frequency, we use the equation given by Planck, which is:

$E=h\nu$

where,

E = energy of the light

h = Planck's constant = $6.62\times 10^{-34}Js$

$\nu$ = frequency of the light = $7.5\times 10^{14}s^{-1}$

Putting values in above equation, we get:

$E=6.62\times 10^{-34}Js\times 7.5\times 10^{14}s^{-1}=49.65\times 10^{-20}J$

Hence, the energy associated with blue light is $49.65\times 10^{-20}J$

Answer 2

A) c = 3 x 10^8 m/s 
f = 7.15 x 10^14 Hz 
c = λ x f (=) λ = 3 x 10^8 / 7.15 x 10^14 = 4.19 x 10^-7 m = 419.6 nm 

B) E = h  f 
H = Planck's constant = 6.63 x 10^-34 J/s 
E = 6.63 x 10^-34 x 7.15 x 10^14 = 4.74 x 10^-19 J