Electricity and Magnetic Fundamentals

41. Another term for corona discharge.

1. Lightning
2. Sparking
3. Aurora
4. Corona Effect

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42. As the magnetic intensity decreases, the relative permeability of a magnetic material

1. decreases
2. remains the same
3. increases
4. becomes zero

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43. At/m is a unit of

1. mmf
2. magnetic force
3. reluctance
4. magnetic flux density

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44. Back emf refers to the

1. Current equal to the applied emf
2. Opposing emf
3. Current opposing the applied emf
4. Voltage opposing the applied emf

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45. Bonding of atoms that is due to the force of attraction between positive ions and a group of negative ions

1. Ionic bond
2. Covalent Bond
3. Electrostatic Bond
4. Metallic bond

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46. Calculate the flux density that will be produced by the field intensity of 2000 a. t/m for a permeability of 126 x 10∧-6 T/A.t/m

1. 0.252 G
2. 0.252 x 10∧-2 T
3. O.252 T
4. 0.252 x 10∧-2 G

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47. Calculate the permeability (in T/A. t/m) of a magnetic material that has a relative permeability of 300

1. 3.78 x 10∧-4
2. 3.78 x 10∧-5
3. 3.78 x 10∧-3
4. 3.78 x 10∧-6

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48. Cobalt is an example of a _________ material.

1. Paramagnetic
2. Diamagnetic
3. Ferromagnetic
4. Non- magnetic

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49. Core materials of a good relay have _________ hysteresis loop.

1. large
2. narrow
3. very large
4. very narrow

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50. Define as that pole which when placed in air from a similar and equal pole repels it with a force of newtons

1. North pole
2. South pole
3. Unit pole
4. Magnetic pole

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