NTA Abhyas JEE Main2020PhysicsAtomic PhysicsPractice
The K α line obtained for molybdenum ( Z = 42 ) is 0.71 A ∘ . Then, the wavelength of the K α line of copper ( Z = 29 ) is
Options
- A2.14 A ∘
- B1.52  A ∘
- C1.04  A ∘
- D0.71  A ∘
Correct answer
B. 1.52  A ∘
Step-by-step solution
λ min ∝ 1 Z - 1 2 ∴ λ Cu λ Mo = Z Mo - 1 2 Z Cu - 1 2 = 4 1 2 2 8 2 = 2.14 ∴    λ Cu = 2.14 × 0.71 A ∘ = 1.52   A ∘