According to modern physics, the wave like (de Broglie) properties of electrons are directly used in which of the following practical applications?

Introduction / Context:
This question checks your understanding of de Broglie wave concept and how wave like behaviour of matter particles, especially electrons, is used in real world devices. Quantum mechanics states that particles such as electrons exhibit both wave and particle characteristics. In particular, the wavelength associated with electrons can be very small, allowing them to act as probes with much finer resolving power than visible light. Knowing which application exploits this property helps you connect abstract theory with concrete technology.

Given Data / Assumptions:

• Electrons are treated as matter waves with de Broglie wavelength.
• Options mention magnifying objects, lasers and weather reports.
• We assume ordinary lasers that use electronic transitions, not special electron beam devices.
• Weather reports typically use satellite and radar data, not electron wave properties.

Concept / Approach:
The de Broglie wavelength of a particle is given by lambda = h / p, where h is Planck constant and p is momentum. For electrons accelerated through suitable voltages, this wavelength can be comparable to or smaller than interatomic distances. Waves with such short wavelengths can resolve extremely small structures, far beyond the limit of optical microscopes that use visible light. Electron microscopes use focused beams of electrons and exploit their wave nature to form high resolution images. Lasers primarily rely on stimulated emission of photons in atomic or semiconductor systems, not directly on electron de Broglie waves, and weather reporting uses macroscopic electromagnetic waves like radar, not electron matter waves.

Step-by-Step Solution:
Step 1: Recall that de Broglie proposed that particles such as electrons have an associated wavelength lambda = h / p. Step 2: Recognise that for fast electrons, lambda is very small, allowing the wave to probe structures on atomic and molecular scales. Step 3: Understand that an electron microscope uses a beam of electrons, shaped and focused similarly to how lenses focus light, to form images of very tiny objects. Step 4: Note that the resolving power of a microscope is proportional to 1 / lambda, meaning shorter wavelength gives better resolution, which is the key advantage of electron waves. Step 5: Conclude that magnifying extremely small objects in electron microscopes is the application that directly uses the wave like properties of electrons.

Verification / Alternative check:
Think about what lasers and weather systems rely on. Lasers are based on stimulated emission and population inversion in atoms or semiconductors, producing coherent photon beams. While electrons are involved in pumping processes, the key wave used is the light wave, not the de Broglie wave of electrons. Weather reports involve use of visible and infrared satellite images and radar signals in the radio or microwave region, again electromagnetic waves, not electron matter waves. Only electron microscopes specifically benefit from electron diffraction and interference, which are direct consequences of their wave nature.

Why Other Options Are Wrong:
Producing coherent light in ordinary lasers mainly uses photon properties and atomic energy levels; de Broglie wavelength of electrons is not the core operating principle. Weather reports rely on large scale meteorological measurements, satellites and radar, not on the microscopic wave properties of electrons. All of the above is incorrect because only electron microscopy, among the listed options, directly exploits electron wave behaviour for imaging.

Common Pitfalls:
Students sometimes see the word laser and associate it vaguely with all advanced quantum effects, including de Broglie waves, leading them to choose lasers incorrectly. Another error is to assume that any technology involving electronics must automatically rely on electron wave properties. To avoid confusion, remember that electron microscopes specifically use electron diffraction and interference, while lasers and weather systems are based on electromagnetic waves at much larger scales.

Final Answer:
The wave like properties of electrons are practically used in magnifying extremely small objects in electron microscopes.