Electrical Online Test 1
Category –EE Online Test
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Attempt Free Electrical Online Test 1 Here. Read The Important Electrical MCQ From Below.
1). Permanent magnets are normally made of
A. alnico alloys
B. aluminium
C. cast iron
D. wrought iron
Ans- A. alnico alloys
2). Permeability in a magnetic circuit corresponds to______ in an electric circuit.
A. resistance
B. resistivity
C. conductivity
D. conductance
Ans- C. conductivity
3). Hard steel is suitable for making permanent magnets because
A. it has good residual magnetism
B. its hysteresis loop has large area
C. its mechanical strength is high
D. its mechanical strength is low
Ans-A. it has good residual magnetism
4). Conductance is analogous to
A. permeance
B. reluctance
C. flux
D. inductance
Ans-A. permeance
5). 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
Ans-A. time constant remains unchanged
6). Conductivity is analogous to
A. retentivity
B. resistivity
C. permeability
D. inductance
Ans-C. permeability
7). The unit of magnetic flux is
A. henry
B. weber
C. ampereturn/weber
D. ampere/metre
Ans-B. weber
8). Relative permeability of vacuum is
A. 1
B. 1 H/m
C. 1/4JI
D. 4n x 10-‘ H/m
Ans-A.1
9). While comparing magnetic and electric circuits, the flux of magnetic circuit is compared with which parameter of electrical circuit ?
A. E.m.f.
B. Current
C. Current density
D. Conductivity
Ans-B. Current
10).The unit of retentivity is
A. weber
B. weber/sq. m
C. ampere turn/metre
D. ampere turn
Ans-B. weber/sq. m
Electrical Online Test 1
11). In a magnetic material hysteresis loss takes place primarily due to
A. rapid reversals of its magnetisation
B. flux density lagging behind magnetising force
C. molecular friction
D. it high retentivity
Ans-D. it high retentivity
12). A material for good magnetic memory should have
A. low hysteresis loss
B. high permeability
C. low retentivity
D. high retentivity
Ans-D. high retentivity
13). Those magnetic materials are best suited for making armature and transformer cores which have____permeability and_______hystersis loss.
A. high, high
B. low, high
C. high, low
D. low, low
Ans-C. high, low
Electrical Online Test 1
14). 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
Ans-B. at the start of the current flow
15). The property of a material which opposes the creation of magnetic flux in it is known as
A. reluctivity
B. magnetomotive force
C. permeance
D. reluctance
Ans-D. reluctance
Electrical Online Test 1
16). 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
Ans-B. high, high
17). Point out the wrong statement. Magnetic leakage is undesirable in electric machines because it
A. lowers their power efficiency
B. increases their cost of manufacture
C. leads to their increased weight
D. produces fringing
Ans-A. lowers their power efficiency
18). 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
Ans-D. Ferrites have high hysteresis
19). In a magnetic material hysteresis loss takes place primarily due to
A. Rapid reversals of its magnetisation
B. Flux density lagging behind magnetising force
C. Molecular friction
D. It high retentivity
Ans-D. It high retentivity
Electrical Online Test 1
20). Silicon steel is used in electrical machines because it has
A. Low co-ercivity
B. Low retentivity
C. Low hysteresis loss
D. High co-ercivity
Ans-C. Low hysteresis loss
21). Laminated cores, in electrical machines, are used to reduce
A. Copper loss
B. Eddy current loss
C. Hysteresis loss
D. All of the above
Ans-B. Eddy current loss
22). The unit of reluctance is
A. Meter/Henry
B. Henry/Meter
C. Henry
D. 1/Henry
Ans-C. Henry
Electrical Online Test 1
