What is the photon energy of red light having a wavelength of $6.40 \times 10 ^ { 2 } \mathrm {~nm} ? \left( c = 3.00 \times 10 ^ { 8 } \mathrm {~m} / \mathrm { s } , h \right.$ $= 6.626 \times 10 ^ { - 34 } \mathrm {~J} \cdot \mathrm { s }$ )
A) $3.11 \times 10 ^ { - 19 } \mathrm {~J}$
B) $1.94 \times 10 ^ { - 19 } \mathrm {~J}$
C) $1.13 \times 10 ^ { - 19 } \mathrm {~J}$
D) $1.31 \times 10 ^ { - 19 } \mathrm {~J}$

Question

Quizplus · Accepted Answer

The photon energy is given by $E = hc/\lambda$, where $h$ is Planck's constant, $c$ is the speed of light, and $\lambda$ is the wavelength. Substituting the given values, we get:$$E = (6.626 \times 10^{-34} \mathrm{J} \cdot \mathrm{s})(3.00 \times 10^8 \mathrm{m/s})/(6.40 \times 10^2 \mathrm{nm})$$$$= (6.626 \times 10^{-34} \mathrm{J} \cdot \mathrm{s})(3.00 \times 10^8 \mathrm{m/s})/(6.40 \times 10^2 \mathrm{nm})(10^{-9} \mathrm{m/nm})$$$$= 3.11 \times 10^{-19} \mathrm{J}$$Therefore, the correct answer is A.

What Is the Photon Energy of Red Light Having a Wavelength