Question

The energy of a photon of wavelength $(\lambda) = 1 m$ is (Planck’s constant $= 6.626\times 10^{-34} Js$ , speed of light $= 3 \times 10^8ms^{-2}$)

• A. $1.988 \times 10^{-23}J$
• B. $1.988 \times 10^{-28}J$
• C. $1.988 \times 10^{-30}J$
• D. $1.988 \times 10^{-25}J$

Answer 1

Answer: (A)

Given, wavelength of photon $= 1\,m$
Speed of light $= 3 \times10^8\,ms^{-1}$
Energy of photon $=\frac{hc}{\lambda}$
Substituting the values in above equation
we get, $E=\frac{6.626\times10^{-34}\,Js\times3\times10^{8}\,ms^{-1}}{1 \,m}$
$=1.988\times10^{-23}\,J$