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Atomic spectra
Class 12 · Physics · 8 questions
Name: ____________________ Date: ____________
In the Bohr model, electrons orbit in:
- A Any orbit
- B Elliptical only
- C Straight lines
- D Fixed energy levels
The Lyman series corresponds to transitions ending at:
- A n = 3
- B n = 1
- C n = 4
- D n = 2
X rays are produced when fast electrons:
- A Are slowed in water only
- B Hit a metal target
- C Are reflected by glass
- D Pass through air
LASER stands for light amplification by:
- A Stimulated emission of radiation
- B Selective emission of rays
- C Spontaneous emission of rays
- D Stimulated electrons
The wavelength emitted when an atom jumps between levels depends on:
- A The energy difference of the levels
- B The temperature only
- C Its mass
- D The atom's colour
An atom emits light when an electron:
- A Stays still
- B Falls to a lower energy level
- C Leaves the atom permanently only
- D Moves to a higher level
The energy of the nth level of hydrogen is proportional to:
- A n
- B n²
- C -1 / n²
- D 1 / n
In a laser, the light is:
- A Only sound
- B Random and white
- C Only infrared
- D Coherent and monochromatic
Answer key
1. D, 2. B, 3. B, 4. A, 5. A, 6. B, 7. C, 8. D
Only certain orbits with fixed energies are allowed.
Lyman lines are in the ultraviolet and end at n = 1.
Sudden deceleration of electrons in a target produces X rays.
This is the meaning of the word.
E = h c / wavelength equals the energy difference.
The energy difference is released as a photon.
E_n = -13.6 / n² eV.
The photons are in phase and of one wavelength.