A Level Physics Practice Exam

Which type of experiment would best demonstrate the wave-like nature of electrons?

1. Photoelectric effect experiment

2. Electron diffraction through a crystal lattice

3. Measurement of electron charge

4. Mass spectrometry of electrons

The correct answer is: Electron diffraction through a crystal lattice

To demonstrate the wave-like nature of electrons, an experiment that showcases phenomena typical of waves is essential. The process of electron diffraction through a crystal lattice illustrates this perfectly. In this experiment, electrons are directed at a crystalline material, and as they pass through the lattice structure, they exhibit diffraction patterns similar to those seen with light waves passing through a narrow slit or around barriers. This diffraction occurs due to the wave characteristics of electrons, as described by de Broglie's hypothesis, which relates the wavelength of a particle to its momentum. When electrons are subjected to a regular array of atoms in a crystal, they interfere with each other due to their wave properties, creating distinct bright and dark spots on a detecting surface. This diffraction pattern serves as compelling evidence of electron behavior aligned with wave phenomena, reinforcing the concept that particles, such as electrons, can exhibit wave-like characteristics. In contrast, other experiments listed do not primarily highlight the wave-like nature of electrons. For example, the photoelectric effect demonstrates the particle-like nature of electrons, showing how light can eject electrons from a material. Measurement of electron charge focuses on the quantification of charge rather than wave characteristics. Lastly, mass spectrometry analyzes the mass and charge of ions without addressing their wave properties. Thus