question_answer

Electrons having KE 15 eV is collided with hydrogen atom and 80.6% of it is used to excite the electrons from its ground state. Find the number of emitted wavelengths.

A)  1                                

B)  2

C)  3                                

D)  4

Correct Answer: C

Solution :

\[\frac{80.6}{100}\times 15=\Delta E\]                      \[=12.09\] \[=|{{E}_{3}}-{{E}_{1}}|\] So, \[{{e}^{-1}}\]can make the hydrogen atom to go into 2nd exited state ie, n = 3 energy state. From this 3 transitions are possible ie, from 3 to 2, 3 to 1 and 2 to 1.