جوہری طیف

In the Bohr model, electrons orbit in:

• 1 Any orbit
• 2 Elliptical only
• 3 Straight lines
• 4 Fixed energy levels

The Lyman series corresponds to transitions ending at:

• 1 n = 3
• 2 n = 1
• 3 n = 4
• 4 n = 2

X rays are produced when fast electrons:

• 1 Are slowed in water only
• 2 Hit a metal target
• 3 Are reflected by glass
• 4 Pass through air

LASER stands for light amplification by:

• 1 Stimulated emission of radiation
• 2 Selective emission of rays
• 3 Spontaneous emission of rays
• 4 Stimulated electrons

The wavelength emitted when an atom jumps between levels depends on:

• 1 The energy difference of the levels
• 2 The temperature only
• 3 Its mass
• 4 The atom's colour

An atom emits light when an electron:

• 1 Stays still
• 2 Falls to a lower energy level
• 3 Leaves the atom permanently only
• 4 Moves to a higher level

The energy of the nth level of hydrogen is proportional to:

• 1 n
• 2 n²
• 3 -1 / n²
• 4 1 / n

In a laser, the light is:

• 1 Only sound
• 2 Random and white
• 3 Only infrared
• 4 Coherent and monochromatic