What is the energy of a photon with a frequency of [tex]$3.6 \times 10^{15} Hz$[/tex]?

Planck's constant is [tex]$6.63 \times 10^{-34} J \cdot s$[/tex].

A. [tex][tex]$1.8 \times 10^{-49} J$[/tex][/tex]
B. [tex]$2.4 \times 10^{-19} J$[/tex]
C. [tex]$1.8 \times 10^{-18} J$[/tex]
D. [tex][tex]$2.4 \times 10^{-18} J$[/tex][/tex]



Answer :

To determine the energy of a photon, we use the formula from quantum mechanics which relates the energy [tex]\( E \)[/tex] of a photon to its frequency [tex]\( f \)[/tex]:

[tex]\[ E = hf \][/tex]

Here:
- [tex]\( h \)[/tex] is Planck's constant, valued at [tex]\( 6.63 \times 10^{-34} \, \text{J} \cdot \text{s} \)[/tex].
- [tex]\( f \)[/tex] is the frequency of the photon, given as [tex]\( 3.6 \times 10^{15} \, \text{Hz} \)[/tex].

Let's perform the calculation step-by-step:

1. Substitute the values into the equation:
[tex]\[ E = (6.63 \times 10^{-34} \, \text{J} \cdot \text{s}) \times (3.6 \times 10^{15} \, \text{Hz}) \][/tex]

2. Write out the multiplication:
[tex]\[ E = 6.63 \times 3.6 \times 10^{-34} \times 10^{15} \, \text{J} \][/tex]

3. Multiply the constants:
[tex]\[ 6.63 \times 3.6 = 23.868 \][/tex]

4. Combine the exponents of 10:
[tex]\[ 10^{-34} \times 10^{15} = 10^{-19} \][/tex]

5. Combine the results:
[tex]\[ E = 23.868 \times 10^{-19} \, \text{J} \][/tex]

6. Convert the answer into scientific notation (keeping two significant figures, as the given choices are in this format):
[tex]\[ 23.868 \times 10^{-19} = 2.3868 \times 10^{-18} \, \text{J} \][/tex]

After reviewing the significant figures and matching it to the closest option given in the possible answers, we find the correct option:

[tex]\[ 2.4 \times 10^{-18} \, \text{J} \][/tex]

Thus, the energy of a photon with a frequency of [tex]\( 3.6 \times 10^{15} \, \text{Hz} \)[/tex] is:

[tex]\[ \boxed{2.4 \times 10^{-18} \, \text{J}} \][/tex]