RRB JE electrical practice paper-2 | RRB JE Electrical

Ques.21. Hopkinson’s test for DC motor is conducted with

1. Full load
2. Half load
3. Low load
4. No load

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Ques.22. In a safety fuse, the temperature to which the wire gets heated is directly proportional to the

1. Square of the current
2. Fourth power of the current
3. Cube of the current
4. None of these

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Ques.23. The number of brushes in the commutator depends upon

1. Speed of the armature
2. Voltage
3. Amount of current to be collected
4. Type of winding

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Ques.24. When a material becomes a superconductor, it resistivity becomes

1. Zero
2. Very small
3. Large
4. About 20% of the normal value

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Ques.25. Assertion (A): A hot wire ammeter has a cramped scale

Reason (R): The heat is proportional to the square of the current

1. Both A and R are true and R is the correct explanation of A
2. Both A and R are true but R is not the correct explanation of A
3. A is true but R is false
4. A is false but R is true

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Ques.26. The number of poles of a 3-phase induction motor, when the speed of motors is 500 RPM and supply frequency is 50 Hz is

1. 8
2. 10
3. 12
4. 15

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Ques.27. Nodal analysis is based on

1. Kirchhoff’s current law
2. Kirchhoff’s voltage law
3. Law of conservation of energy
4. Law of conservation of momentum

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Ques.28. The tunnel diode is made of the semiconductors which are

1. Highly Doped
2. Sparsely Doped
3. Intrinsic
4. Normally doped

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Ques.29. In a transformer the resistance between its primary and secondary is

1. Zero
2. Infinite
3. 10⁻³ Ω
4. 10⁵ Ω

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Ques.30. Which of the following applications a DC motor is preferred over an AC motor?

1. Variable speed operation
2. High speed operation
3. Low speed operation
4. Fixed speed operation

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