Physics
Electrical Machines and Circuits
754 Questions
Electrical machines and circuits involve the principles of alternating and direct current, transformers, diodes, and power consumption. These concepts are essential for engineering and technical exams. Review these practice questions to test your knowledge of circuit analysis.
Transformers and impedanceAlternating and direct currentCircuit components and diodesPower consumption calculations
Electrical Machines and Circuits Questions
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converting of DC into AC
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regulating the fluctuation of voltage
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measuring the flow of electricity
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converting low voltage into high voltage and vice versa
D
Correct answer
Explanation
A transformer is an electrical device used to step up or step down alternating current (AC) voltage levels through electromagnetic induction. It does not convert DC to AC, nor is it a measuring instrument.
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high d.c. to low d.c
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high a.c. to low a.c
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d.c. to a.c
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a.c. to d.c
D
Correct answer
Explanation
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, into direct current (DC), which flows in only one direction.
A
Correct answer
Explanation
SMPS stands For Switch Mode power Supply. It takes 220V AC supply as Input And convert ist into DC volt.
C
Correct answer
Explanation
To connect n locations in a full mesh topology, the number of circuits is calculated as n(n-1)/2. For n=4, this is 4(3)/2 = 6.
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direct flow of current between two points of different potential
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indirect flow of current between two points
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direct flow of current between points of the same potential
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None of these
A
Correct answer
Explanation
A short circuit occurs when current flows directly between two points at different electrical potentials, bypassing the normal load or resistance in the circuit. This creates a low-resistance path that can cause excessive current flow, potentially damaging equipment or causing fires.
D
Correct answer
Explanation
230V voltage selection is for India because of the frequency of electricity in India.
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diode
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capacitor
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transformer
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transistor
A
Correct answer
Explanation
Diode is an electrical device which is used to convert AC into pulsating DC voltage. The circuit which is made by 2 or 4 diodes to rectify the AC into pulsating DC, which is called rectifier.
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transformer
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capacitor
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modem
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rectifier
C
Correct answer
Explanation
It is used to modulate or convert digital signal to analog signals and the process is called modulation.
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Only a.
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Only a and b
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Only b
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Only b and c
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Only c
A
Correct answer
Explanation
The less the thickness of the connecting wire, the more is the current it can bear without getting hot, is a false statement. Hence, it is the correct option. The more the thickness of the connecting wire, the more is the current it can bear without getting hot.
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Element
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Closed electric circuit
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Miniature circuit breaker
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Open electric circuit
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Electromagnet
C
Correct answer
Explanation
This is the correct option. Miniature circuit breaker automatically turns off when current in a circuit exceeds the safe limit.
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neutral wire
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earth wire
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live wire
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none of these
A
Correct answer
Explanation
Wires are of different colours so as to distinguish between live wire, neutral wire and earth wire.
They are of three different colours-
live wire: red colour
neutral wire: black colour
earth wire: green colour
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2000 volts to 4000 volts
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4000 volts to 6000 volts
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10000 volts to 12000 volts
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12000 volts to 25000 volts
D
Correct answer
Explanation
12000 volts to 25000 volts
D
Correct answer
Explanation
Standard TTL (Transistor-Transistor Logic) circuits are designed to operate from a 5V power supply.
B
Correct answer
Explanation
The efficiency of a full-wave rectifier is calculated as 81.2 percent, which is double that of a half-wave rectifier (40.6 percent).
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50 Hz
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100 Hz
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200 Hz
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400 Hz
B
Correct answer
Explanation
In a full-wave rectifier, the output frequency is twice the input frequency because both half-cycles of the input AC are rectified into the same polarity.