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Assignment Questions - 14180_185

Neets Module 08-Introduction to Amplifiers
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18 2-52.   If the permeability of the core of a coil decreases, what happens to the (a) inductance and (b) true power in the circuit? 1.     (a) Increases (b) increases 2.     (a) Increases (b) decreases 3.     (a) Decreases (b) increases 4.     (a) Decreases (b) decreases 2-53.   If the current in an iron-core coil is increased to a large value (from the operating point) what happens to the permeability of the core? 1.    It increases 2.    It decreases 3.    It remains the same 4.    It increases initially and then decreases rapidly 2-54.   If two coils are wound on a single iron core, a change in current in one coil (a) will or will not cause a change in inductance and (b) will or will not cause a change in current in the other coil. 1.     (a) Will (b) will 2.     (a) Will (b) will not 3.     (a) Will not (b) will 4.     (a) Will not (b) will not Figure 2H.—Saturable-core reactor. IN ANSWERING QUESTION 2-55, REFER TO FIGURE 2H. 2-55.   What portion of the schematic diagram indicates a saturable core? 1.     a 2.     b 3.     c 4.     d 2-56.   A magnetic amplifier should be operated on what portion of the magnetization curve? 1.     The positive peak 2.     The negative peak 3.     The mid-point 4.     The knee 2-57.   A toroidal core is used in a saturable-core reactor to counteract which of the following effects? 1.    Hysteresis 2.    Copper loss 3.    Both 1 and 2 above 4.    The effect of load flux on control flux 2-58.   Why is a rectifier used in a magnetic amplifier? 1.     To decrease current 2.     To eliminate hysteresis loss 3.     To increase the power-handling capability 4.     To convert the magnetic amplifier from an a.c. device to a d.c. device. 2-59.   What can be used to set a magnetic amplifier to the proper operating point and leave the control winding free to accept input signals? 1.     A filter 2.     A bias winding 3.     A d.c. power source 4.     A feedback network 2-60.   A magnetic amplifier would not be used in which of the following devices? 1.    A servo system 2.    A d.c. power supply 3.    Temperature indicators 4.    A wideband audio power amplifier system






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