Concepts Of Physics MCQ Edition [Volume 2]PhysicsBohr's Model and Physics of the Atom
Determine the smallest wavelength of radiation that can be emitted by He ^+ .
Options
- A364 nm
- B46 nm
- C23 nm
- D91 nm
Correct answer
C. 23 nm
Step-by-step solution
The smallest wavelength of radiation corresponds to the maximum energy transition, which occurs when an electron transitions from n₂ = to n₁ = 1 . Using the Rydberg formula: 1 = R_H Z^2 ( 1 n₁^2 - 1 n₂^2 ) For He ^+ , the atomic number Z = 2 . Substituting the values: 1 = R_H (2)^2 ( 1 1^2 - 1 ^2 ) 1 = 4 R_H = 1 4 R_H We know that 1 R_H 91.2 nm . = 91.2 4 nm = 22.8 nm 23 nm