Discussion Forum



1)

Energy of an electron is given by

   $E=-2.178 \times 10^{-18}J \left(\frac{Z^{2}}{n^{2}}\right)$

 Wavelength of light requires to excite an electron in an hydrogen atom from level n=1 to n=2 will  be (h= 6.62 x 10-34 J s and c=3.0 x 108 ms-1)


A) $1.214 \times 10^{-7}m$

B) $2.816 \times 10^{-7}m$

C) $6.500 \times 10^{-7}m$

D) $8.500 \times 10^{-7}m$

Answer:

Option A

Explanation:

$\triangle E=2.178 \times 10^{-18}\left(\frac{1}{1^{2}}-\frac{1}{2^{2}}\right)=\frac{hc}{\lambda}$

              $2.178 \times 10^{-18}\left(\frac{1}{1^{2}}-\frac{1}{2^{2}}\right)$

  =$\frac{6.62\times 10^{-34}\times3.0 \times 10^{8}}{\lambda}=1.21 \times 10^{-7}m$