Question

If an electron made a transition from $n=4$ to $n=2$ level, the wavelength of the light that it would emit is nearly

• A. $380nm$
• B. $190nm$
• C. $76nm$
• D. $510nm$

Answer 1

The correct option is A $380nm$

Let wavelength emitted during the transaction from $n=4$ to $n=2$ be ${\lambda }_{4\to 2}$

Using : $\frac{1}{{\lambda }_{4\to 2}}$ $=\frac{1}{{\lambda }_{4\to 1}}-$ $\frac{1}{{\lambda }_{2\to 1}}$

$\therefore$ $\frac{1}{{\lambda }_{4\to 2}}$ $=\frac{1}{75.63}-$ $\frac{1}{94.54}$

$⟹$ ${\lambda }_{4\to 2}=380$ $nm$