Answer :
Answer:
Explanation:
The energy of a quantum of light with frequency v is given by
[tex]E=hv[/tex]where h = planck's constant = 6.63 *10^-34 and v = frequency of light.
Now in our case, we are told that
[tex]v=4.21\times10^{11}\times10^3Hz[/tex]The extra 10^3 comes from the fact that we were given kilohertz (and not simply hertz).
Substituting the value of the given frequency and the Planck's constant into the above equation gives
[tex]E=(6.63\times10^{-34})\times(4.21\times10^{11}\times10^3)[/tex]which upon evaluating gives
[tex]\boxed{E=2.79\times10^{-19}J}[/tex]Hence, the energy of our quantum of light is 2.79*10^-19 Joules!