Free Practice Question
RC · Reading Comprehension
605-655
Short Passage - Science
Reading Passage
Within a couple of weeks after the announcement of superconductivity in MgB2, we had devised a technique for making wire segments of this remarkable superconductor. MgB2 can be formed by reacting magnesium vapor with boron, a process that can take place within hours at temperatures near 1,000 degrees Celsius: the boron essentially sucks the magnesium vapor out of the environment and becomes MgB2. This process works with boron fibers that can be purchased in lengths of hundreds of meters; it has been applied to filaments with starting diameters ranging from 0.1 to 0.3 millimeter.
Wire segments such as these are very useful for basic research, allowing for the measurement of the intrinsic physical properties of MgB2. Before such wire segments could be used in practical applications, they would need to have a conductive, malleable sheath to provide structural support. A suitable sheath has not yet been developed.
A more common method of wire synthesis is called “powder in a tube.” This technique involves pouring powdered magnesium and boron or powdered MgB2 into a tube, drawing the tube into a wire, and then reacting or annealing the wire to produce a solid structure. This technique has produced research samples that range from tens to hundreds of meters long. Despite MgB2 being a rather young superconductor, companies have been taking notice and are working toward commercializing it. Examples include Diboride Conductors and Hyper Tech Research, which are small companies focusing on making and improving the properties of MgB2 wires.
Wire segments such as these are very useful for basic research, allowing for the measurement of the intrinsic physical properties of MgB2. Before such wire segments could be used in practical applications, they would need to have a conductive, malleable sheath to provide structural support. A suitable sheath has not yet been developed.
A more common method of wire synthesis is called “powder in a tube.” This technique involves pouring powdered magnesium and boron or powdered MgB2 into a tube, drawing the tube into a wire, and then reacting or annealing the wire to produce a solid structure. This technique has produced research samples that range from tens to hundreds of meters long. Despite MgB2 being a rather young superconductor, companies have been taking notice and are working toward commercializing it. Examples include Diboride Conductors and Hyper Tech Research, which are small companies focusing on making and improving the properties of MgB2 wires.
The primary purpose of the passage is:
Answer Choices
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to describe the history of MgB2
B
introduce and detail MgB2 and how it can be formed and made useful
C
detail how the wire segments work in a superconductor called MgB2
D
to reason how boron fiber can be used to make MgB2 and its wire segments
E
enlist different procedures and techniques to form MgB2 and its wire segments
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Difficulty
605-655
Type
RC
Category