A Level Physics Practice Exam

What does the de Broglie wavelength represent?

1. The frequency of electromagnetic radiation

2. The wavelength of a matter particle

3. The distance between wave peaks

4. The speed of light in a vacuum

The correct answer is: The wavelength of a matter particle

The de Broglie wavelength represents the wavelength associated with a matter particle, reflecting the wave-particle duality of matter. This concept, introduced by Louis de Broglie, suggests that particles such as electrons can exhibit wave-like properties, including wavelength, in addition to their particle characteristics. The wavelength can be calculated using the de Broglie equation: \[ \lambda = \frac{h}{p} \] where \( \lambda \) is the de Broglie wavelength, \( h \) is Planck's constant, and \( p \) is the momentum of the particle. This relationship highlights that as the momentum of a particle increases, its wavelength decreases, indicating a closer association with classical particle behavior. Conversely, for very small momentum (light particles), their wave nature becomes more pronounced, with longer wavelengths. This concept is foundational in quantum mechanics, as it helps explain phenomena such as electron diffraction and the behavior of particles at atomic and subatomic scales. Understanding the de Broglie wavelength allows physicists to better grasp the strange nature of quantum objects and their interactions.