# Magnetic Circuit

• ## When both the inductance and resistance of a coil are doubled the value of_____.

• A. Time constant remains unchanged
• B. Initial rate of rise of current is doubled
• C. Final steady current is doubled
• D. Time constant is halved
Explanation:

No answer description available for this question

• ## Those materials are well suited for making permanent magnets which have _____ retentivity and _____ coercivity.

• A. Low, high
• B. High, high
• C. High, low
• D. Low, low
Explanation:

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• ## The relative permeability of a ferromagnetic material is_____.

• A. Less than one
• B. More than one
• C. More than 10
• D. More than 100 Ωr 1000
Explanation:

No answer description available for this question

• ## Those magnetic materials are best suited for making armature and transformer cores which have ____permeability and ____hysteresis loss.

• A. High, high
• B. Low, high
• C. High, low
• D. Low, low
Explanation:

No answer description available for this question

• ## The rate of rise of current through an inductive coil is maximum_____.

• A. At 63.2% of its maximum steady value
• B. At the start of the current flow
• C. After one time constant
• D. Near the final maximum value of current
Explanation:

No answer description available for this question

• ## A ferrite core has less eddy current loss than an iron core because_____.

• A. Ferrites have high resistance
• B. Ferrites are magnetic
• C. Ferrites have low permeability
• D. Ferrites have high hysteresis
Explanation:

No answer description available for this question

• ## Silicon steel is used in electrical machines because it has_____.

• A. Low coercivity
• B. Low retentivity
• C. Low hysteresis loss
• D. High coercivity
Explanation:

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• ## Laminated cores, in electrical machines, are used to reduce_____.

• A. Copper loss
• B. Eddy current loss
• C. Hysteresis loss
• D. All of the above
Explanation:

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• ## Energy stored by a coil is doubled when its current is increased by percent.

• A. 25
• B. 50.14
• C. 41.4
• D. 100
Explanation:

No answer description available for this question

• ## The property of a material which opposes the creation of magnetic flux in it is known as_____.

• A. Reluctivity
• B. Magneto-motive force
• C. Permeance
• D. Reluctance