Answer
$5.4\times10^{-20}J$ or $0.34 eV$
Work Step by Step
The energy is quantized according to equation 27–3, E = nhf. The difference in energy between successive levels is $\Delta E = hf$.
$$\Delta E = hf=(6.63\times10^{-34}J \cdot s)(8.1\times10^{13}Hz)=5.4\times10^{-20}J$$
Converted to electron volts, the answer is 0.34 eV.
