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What is the most popular and efficient type of transformer core?
Shell core
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Which type of transformers are those in which the secondary voltage is in phase with the primary?
Likewound
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What is defined as the magnetomotive force developed by one ampere of current flowing in a coil of one turn?
Ampere-turn
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What is done to transformer cores to minimize the loss resulting from eddy currents?
Lamination
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Power transformers normally operate from either 60 Hz, or what alternating current?
400 Hz
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The power handling capacity of a transformer is measured in either the volt-ampere unit or what other unit?
Watt
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Which device transfers electrical energy from one circuit to another by electromagnetic induction?
Transformer
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What are lines of flux generated by one winding which do not link with the other winding called?
Leakage Flux
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Generally, air-core transformers are used when the voltage source has a high frequency (above what)?
20 kHz
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Small power transformers used in electrical equipment have an 80 to 90 percent efficiency range, while large, commercial powerline transformers may have efficiencies exceeding what percent?
98
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What is a transformer in which the voltage across the secondary is less than the voltage across the primary called?
Step-down
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Most power transformers are of what type?
Iron-core
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What is established around the winding when an alternating current flows through a primary winding?
Magnetic field
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What is said to exist when a voltage is applied to the primary, but no load is connected to the secondary?
No load condition
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Which type of low-resistance wire are the primary and secondary windings of a transformer usually made of?
Copper
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What indicates the amount by which the transformer increases or decreases the voltage applied to the primary?
Turns ratio
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The total power loss in a transformer is a combination of how many types of losses?
3
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What are used to supply voltages to the various circuits in electrical equipment?
Power transformers
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Radio-frequency (RF) transformers are used to couple circuits to which frequencies above what are applied?
20,000 Hz
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The resistance of the human body cannot be relied upon to prevent a fatal shock from a voltage as low as how many volts or even less?
115
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Tests have shown that body resistance under unfavorable conditions may be as low as 300 ohms, and possibly as low as how many ohms (from temple to temple) if the skin is broken?
100
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