The basic principles that allow an electric motor to operate include all of the following except:
a. electric current creates a magnetic field.
b. magnetic poles attract and repel each other.
c. electric current closes the magnetic field.
d. current direction determines the magnetic poles.
c. electric current closes the magnetic field.
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The noise -reduction coefficient (NRC) of a material is evaluated between the frequency range of 250 Hz and 2 kHz because
A) it is virtually impossible to evaluate this property outside the above frequency range. B) the human ear is insensitive to noise outside the above frequency range. C) most of the sound energy in human speech lies in the given frequency range. D) most of the sound energy in the noise produced in buildings lies in the given frequency range. E) none of the above.
Is it acceptable to add notes to drawings for additional information?
What will be an ideal response?
What type of loads are imposed on a structure from a sudden gust of wind or from an earthquake?
A. dead B. dynamic C. live D. wind
The refrigerant charge in a domestic refrigerator is usually expressed in ____.
A. ounces B. pounds C. grains D. microns