Electricity and Magnetic Fundamentals

81. If a magnetic flux cuts across 200 turns at a rate of 2Wb/s, the induced voltage according to Faraday's law is about

1. 4OO V
2. 100 V
3. 200 V
4. 600 V

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82. If on looking at any one end of a solenoid; the direction of current flow is found to be clockwise then the end under observation is a south pole. This is known as

1. Right hand rule
2. Left hand rule
3. Cork screw rule
4. End Rule

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83. If the distance between two magnetic poles decreases by 2 times, the force between them

1. decreases two times
2. increases four times
3. increases two times
4. decreases four times

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84. If the length and area of cross-section of a wire are doubled, then its resistance

1. becomes four times
2. becomes sixteen times
3. remains the same
4. becomes two times

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85. If the magnetic material is located within a coil through which alternating current (60 Hz frequency) flows, then _________ hysteresis loops will be formed every second.

1. 6O
2. 120
3. 30
4. 180

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86. If the number of valence electrons of an atom is exactly 4, then the substance is called

1. a semiconductor
2. a conductor
3. an insulator
4. a cryogenic conductor

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87. If the number of valence electrons of an atom is less than 4, the substance is called

1. a conductor
2. a semiconductor
3. an insulator
4. a superconductor

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88. If the number of valence electrons of an atom is less than 4, then the substance is probably

1. a metal
2. an insulator
3. a non-metal
4. a semiconductor

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89. If the number of valence electrons of an atom is more than 4, the substance is called

1. a semiconductor
2. a conductor
3. an insulator
4. a semi-insulator

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90. If the relative permittivity of a material is 10, then its permittivity is

1. 4π X 10∧-7 F/m
2. 4π X 10∧-6 F/m
3. 8.854 X 10∧-11 F/m
4. 8.854 X 10∧-12 F/m

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