In latitudes where the subsurface layer of soil always remains frozen, the frozen layer is called
a. an aquifer.
b. the frost table.
c. a glacier.
d. permafrost.
d
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A flat coil of wire consisting of 20 turns, each with an area of 80 cm2, is positioned perpendicularly to a uniform magnetic field that increases its magnitude at a constant rate from 2.0 T to 6.0 T in 2.0 s. If the coil has a total resistance of 0.40 W, what is the magnitude of the induced current?
a. 500 mA c. 140 mA b. 70 mA d. 800 mA
A solid concrete wall 4.0 m by 2.4 m and 30 cm thick, with a thermal conductivity of 1.3 W/(m ? K), separates a basement at 18°C from the ground outside at 6°C. Under steady state conditions, how much heat flows through the wall in one hour?
A) 1.8 MJ B) 1.8 kJ C) 500 J D) 5.0 MJ E) 5.0 kJ
Answer the following statement(s) true (T) or false (F)
1. Equation E18.4 
is also solved by a function f (s), where s = t + x/c.
2. One can in principle create a purely electric traveling electromagnetic wave in empty space 
If a jet plane were to double its MACH-speed, its half-angle will
A) decrease. B) increase. C) stay the same.