Question

The energy per quantum associated with light of wavelength $250\times {10}^{-9}$ m is:

• A. $7.95\times {10}^{-19}J$
• B. $7.95\times {10}^{-26}J$
• C. $3.93\times {10}^{-26}J$
• D. $3.93\times {10}^{-19}J$

Answer 1

The correct option is A $7.95\times {10}^{-19}J$

Use,
$E=hc/\lambda$
$\lambda =250\times {10}^{-9}m$
$E=6.6\times {10}^{-34}\times 3\times {10}^8/(250\times {10}^{-9})J=7.95\times {10}^{-19}J$.