Problem: Please answer a question about the following article about Light-emitting diode:
A P-N junction can convert absorbed light energy into a proportional electric current. The same process is reversed here (i.e. the P-N junction emits light when electrical energy is applied to it). This phenomenon is generally called electroluminescence, which can be defined as the emission of light from a semi-conductor under the influence of an electric field. The charge carriers recombine in a forward-biased P-N junction as the electrons cross from the N-region and recombine with the holes existing in the P-region. Free electrons are in the conduction band of energy levels, while holes are in the valence energy band. Thus the energy level of the holes will be lesser than the energy levels of the electrons. Some portion of the energy must be dissipated in order to recombine the electrons and the holes. This energy is emitted in the form of heat and light.
What is the phenomenon where a P-N junction emits light when an electrical current is applied to it?
A: electroluminescence
Problem: Please answer a question about the following article about Political corruption:
Mobile telecommunications and radio broadcasting help to fight corruption, especially in developing regions like Africa, where other forms of communications are limited. In India, the anti-corruption bureau fights against corruption, and a new ombudsman bill called Jan Lokpal Bill is being prepared.
What country is used as an example for limited forms of communications?
A: Africa
Problem: Please answer a question about the following article about Dissolution of the Soviet Union:
In February 20, 1988, after a week of growing demonstrations in Stepanakert, capital of the Nagorno-Karabakh Autonomous Oblast (the Armenian majority area within Azerbaijan Soviet Socialist Republic), the Regional Soviet voted to secede and join with the Soviet Socialist Republic of Armenia. This local vote in a small, remote part of the Soviet Union made headlines around the world; it was an unprecedented defiance of republic and national authorities. On February 22, 1988, in what became known as the "Askeran clash", two Azerbaijanis were killed by Karabakh police. These deaths, announced on state radio, led to the Sumgait Pogrom. Between February 26 and March 1, the city of Sumgait (Azerbaijan) saw violent anti-Armenian rioting during which 32 people were killed. The authorities totally lost control and occupied the city with paratroopers and tanks; nearly all of the 14,000 Armenian residents of Sumgait fled.
What was triggered by the radio broadcast of the deaths?
A: Sumgait Pogrom
Problem: Please answer a question about the following article about Capacitor:
Capacitors, especially ceramic capacitors, and older designs such as paper capacitors, can absorb sound waves resulting in a microphonic effect. Vibration moves the plates, causing the capacitance to vary, in turn inducing AC current. Some dielectrics also generate piezoelectricity. The resulting interference is especially problematic in audio applications, potentially causing feedback or unintended recording. In the reverse microphonic effect, the varying electric field between the capacitor plates exerts a physical force, moving them as a speaker. This can generate audible sound, but drains energy and stresses the dielectric and the electrolyte, if any.
What is it called when a changing electric field existing between the conductive plates of a capacitor physically moves them?
A:
the reverse microphonic effect