Challenge your understanding of modern physics with this quiz on atoms, atomic nuclei, and semiconductor devices. Explore conceptual frameworks and practical applications in atomic structure, nuclear reactions, and the principles underlying semiconductor technology.
Which model of the atom introduced the idea that electrons occupy specific energy levels or orbits around the nucleus, rather than randomly distributed positions?
Explanation: The Bohr model proposed that electrons orbit the nucleus in fixed energy levels, resolving issues with earlier models about atomic stability and spectral lines. The Dalton model viewed atoms as solid, indivisible spheres without internal structure. The Rutherford model established a dense, positive nucleus but did not specify electron energy levels, and the Thomson model pictured electrons embedded in a 'plum pudding' of positive charge. Thus, only the Bohr model addressed electron energy levels directly.
In radioactive decay, what is emitted during beta-minus decay of a radioactive nucleus such as carbon-14?
Explanation: During beta-minus decay, a neutron in the nucleus is converted into a proton, and an electron (called a beta particle) is emitted. Alpha particles consist of two protons and two neutrons, which are emitted during alpha decay, not beta. A positron is emitted during beta-plus decay, a different process. A proton is not emitted in ordinary beta-minus decay.
Which type of semiconductor device allows current to flow easily in one direction while restricting it in the opposite direction, similar to a one-way street for electric charge?
Explanation: A diode is a semiconductor device that conducts current in one direction only, effectively acting as a one-way street for electric current. Transistors are used for amplification and switching, not for one-way conduction alone. Resistors limit current flow but do not have directionality, while capacitors store and release electrical energy and do not act as one-way conductors.
Which process describes two light atomic nuclei combining to form a heavier nucleus, such as when hydrogen nuclei fuse to form helium in the Sun?
Explanation: Nuclear fusion is the process in which two light nuclei merge to form a heavier nucleus, releasing energy; this happens in stars like the Sun. Nuclear fission is the opposite, splitting a heavy nucleus into lighter ones. Radioactive decay involves an unstable nucleus emitting particles or radiation without combining with others. Ionization refers to the removal or addition of electrons from an atom, not changes in nuclei.
According to band theory, what best distinguishes a semiconductor from a conductor and an insulator in terms of energy bands?
Explanation: A semiconductor is characterized by a small energy gap (band gap) between its valence band and conduction band, allowing electrons to be thermally excited across the gap. Conductors have overlapping or no gap between bands, so electrons move freely, making 'no energy gap at all between bands' incorrect for semiconductors. Insulators have a large band gap, making 'a very large energy gap between bands' incorrect here. 'Completely filled conduction band' describes conductors, not semiconductors.