Question

$1$ mole of photon, each of frequency $2500s^{-1},$ would have approximately a total energy of :

• A. 1 erg
• B. 1 Joule
• C. 1 eV
• D. 1 MeV

Answer 1

Answer: (A)

Frequency of one photon $=2500s^{-1}$
$\therefore$ Frequency of 1 mole of photon
$=6.023\times 10^{23}\times 2500s^{-1}$
Total energy of $1$ mole of photon, $E=hv$
$=6.626\times 10^{-34}Js\times 6.023\times 10^{23}\times 2500s^{-1}$
$=9.97\times 10^{-7}J\approx 10erg$
In option (a) there should be $10$ erg instead of $1$ erg.