The core of an electromagnet is said to be in saturation when:
A. the core is permitted to move freely within the coil
B. an increase in current through the coil causes no further increase in the mmf
C. frequent changes in the direction of current through the coil causes heating effects in the core material
D. changing the polarity of the current in the coil changes the polarity of the magnetic field around the core
E. None of the above
Answer: Option B
This Question Belongs to Computer Science >> Electronic Principles
In an intrinsic semiconductor, the number of free electrons
A. Equals the number of holes
B. Is less than the number of holes
C. Is greater than the number of holes
D. Impossible to say
E. None of the above
A device that converts mechanical into electrical energy is?
A. solar cell
B. thermocouple
C. chemical cell
D. generator
E. None of the above
Which one of the following kinds of materials has the lowest permeability?
A. A diamagnetic material
B. A paramagnetic material
C. A feiTomagnetic material
D. All of the above
E. None of the above
The total impedance of a parallel RLC circuit:
A. always increases as the applied frequency increases
B. is equal to the sum of the values of resistance, inductive reactance and capacitive reactance
C. always decreases as the applied frequency increases
D. is maximum at the resonant frequency
E. None of the above
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