A Level Physics Practice Exam

Why do emitted photons have specific wavelengths in atomic transitions?

1. They are produced by collisions with photons

2. Electromagnetic radiation is emitted when an electron falls between fixed levels

3. Photons are created in random energy levels

4. Electrons always emit energy as heat

The correct answer is: Electromagnetic radiation is emitted when an electron falls between fixed levels

The emission of photons with specific wavelengths during atomic transitions is fundamentally tied to the energy changes that occur when electrons move between quantized energy levels in an atom. When an electron in an atom absorbs energy, it can become excited and move to a higher energy level. This state is unstable, and the electron will eventually return to a lower energy level, a process known as relaxation. The energy difference between these two levels is released in the form of a photon, which carries energy equivalent to this difference. In terms of physics, the energy of a photon is related to its wavelength by the equation \( E = \frac{hc}{\lambda} \), where \( E \) is the energy, \( h \) is Planck’s constant, \( c \) is the speed of light, and \( \lambda \) is the wavelength. Therefore, each transition corresponds to a specific energy difference, and thus, a specific wavelength of the emitted photon. This is why we observe distinct spectral lines for different elements; each element has a unique set of energy levels. The other options do not accurately describe the nature of photon emission in atomic transitions. Collisions with photons do not produce emitted photons directly in this context, and photons are not created