For sodium light, the two yellow lines occur at ${\lambda }_1$ and ${\lambda }_2$ wavelengths. If the mean of these two is $6000 \stackrel{\circ }{\mathrm{A}}$ and $\left|{\lambda }_2-{\lambda }_1\right|=6 \stackrel{\circ }{\mathrm{A}}$, then the approximate energy difference between the two levels corresponding to ${\lambda }_1$ and ${\lambda }_2$ is

• Correct answer
  A

  $2\times {10}^{-3} \text{e}\text{V}$
• B

  $2 \text{e}\text{V}$
• C

  $2000 \text{e}\text{V}$
• D

  $2\times {10}^{-6} \text{e}\text{V}$

Hence, the correct answer is option: 'A'.