Modern Physics - Quantum Mechanics - SS2 Physics Past Questions and Answers - page 3
In the electron diffraction experiment, if the distance between the two slits on the screen is increased, what will happen to the distance between the bright fringes on the screen?
Increase
Decrease
Stay the same
Cannot be determined
The observation of electron diffraction provides evidence for the wave-particle duality of particles. Which theory explains the wave-particle duality of particles?
Quantum mechanics
Special relativity
Classical mechanics
Electromagnetism
Describe the experimental setup and procedure of the electron diffraction experiment. Explain how the diffraction pattern is formed and what it signifies.
In the electron diffraction experiment, a beam of electrons is passed through a narrow slit and directed at a screen containing two slits. The electrons behave as waves and diffracted as they pass through the slits. This leads to the formation of an interference pattern on the screen, characterised by alternating bright and dark fringes.
The diffraction pattern signifies the wave nature of electrons. It demonstrates that particles such as electrons exhibit wave-like properties, such as interference and diffraction. The pattern resembles the interference patterns observed with other types of waves, providing evidence for the wave-particle duality of particles.
Discuss the implications of electron diffraction for our understanding of the wave-particle duality of particles. How does it challenge the classical view of particles?
Electron diffraction provides compelling evidence for the wave-particle duality of particles and challenges the classical view of particles as discrete, localised entities. The observation of interference patterns in electron diffraction experiments suggests that particles, such as electrons, possess wave-like properties.
The diffraction pattern implies that electrons exhibit wave interference, which is a characteristic behaviour of waves. This challenges the classical notion of particles as point-like objects with definite positions and trajectories. Instead, it suggests that particles have a wave nature, characterised by properties such as wavelength, diffraction, and interference.
The wave-particle duality of particles, as demonstrated by electron diffraction, forms the foundation of quantum mechanics. It reveals that particles can exhibit both particle-like and wave-like behaviour, depending on the experimental conditions and observation scale. This understanding has revolutionised our perception of the fundamental nature of particles and their behaviour at the quantum level.
According to the Bohr Model of the atom, electrons exist in specific energy levels. Which of the following statements is true regarding these energy levels?
Electrons can occupy any energy level at random.
Electrons can transition between energy levels without absorbing or emitting energy.
Electrons can only occupy certain discrete energy levels.
Electrons can occupy energy levels continuously without restriction.
The Bohr Model successfully explains which of the following phenomena in atomic spectra?
The continuous spectrum emitted by a heated object.
The emission spectrum of hydrogen.
The absorption spectrum of helium.
The emission spectrum of neon.
According to the Bohr Model, when an electron transitions from a higher energy level to a lower energy level, what happens?
The electron emits a photon of light.
The electron absorbs a photon of light.
The electron gains energy.
The electron loses energy.
The energy difference between two energy levels in the Bohr Model is proportional to:
The speed of the electron.
The mass of the electron.
The radius of the electron's orbit.
The frequency of the emitted photon.
Which of the following statements is true about the limitations of the Bohr Model?
It successfully explains the behaviour of all atoms and molecules.
It accurately predicts the exact energy levels and spectral lines of complex atoms.
It does not account for the wave-particle duality of electrons.
It is consistent with the observations of electron diffraction.
Explain the main postulates of the Bohr Model and how it revolutionised our understanding of atomic structure.
The Bohr Model, proposed by Niels Bohr in 1913, introduced several key postulates that transformed our understanding of atomic structure. Firstly, it suggested that electrons exist in specific quantized energy levels around the nucleus, rather than in continuous orbits. Secondly, it stated that electrons can only transition between these energy levels by either absorbing or emitting discrete amounts of energy in the form of photons. Lastly, the model asserted that the angular momentum of electrons is quantized and that electron orbits must be stable.
The Bohr Model had significant implications for explaining atomic spectra, particularly the emission and absorption spectra of hydrogen. It successfully explained the discrete nature of spectral lines and provided a mathematical framework for predicting the frequencies of emitted or absorbed photons during electron transitions. This model laid the foundation for understanding the electronic structure of atoms and played a crucial role in the development of quantum mechanics.