MAGNETIC CIRCUIT 1(TTA)

1. The unit of magnetic flux is

Henry

Weber

Ampereturn/weber

Ampere/metre

2. Those magnetic materials are best suited for making armature and transformer cores which havepermeability and___hystersis loss.

High,high

Low,high

High,low

Low,low

3. If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be

Zero

Small

Large

None of the above

4. Laminated cores, in electrical machines, are used to reduce

Copper loss

Eddy current loss

Hysteresis loss

All of the above

5. When both the inductance and resistance of a coil are doubled the value of

Time constant remains unchanged

Initial rate of rise of current is doubled

Final steady current is doubled

Time constant is halved

6. Silicon steel is used in electrical machines because it has

Low co-ercivity

Low retentivity

Low hysteresis loss

High co-ercivity

7. Permeability in a magnetic circuit corresponds to______ in an electric circuit.

Resistance

Resistivity

Conductivity

Conductance

8. Conductivity is analogous to

Retentivity

Resistivity

Permeability

Inductance

9. The property of a material which opposes the creation of magnetic flux in it is known as

Reluctivity

Magnetomotive force

Permeance

Reluctance

10. .Permanent magnets are normally made of

Alnico alloys

Aluminium

Cast iron

Wrought iron

11. Conductance is analogous to

Permeance

Reluctance

Flux

Inductance

12. While comparing magnetic and electric circuits, the flux of magnetic circuit is compared with which parameter of electrical circuit ?

E.m.f.

Current

Current density

Conductivity

13. Relative permeability of vacuum is

1

1 H/m

1/4JI

4n x 10-' H/m

14. Point out the wrong statement. Magnetic leakage is undesirable in electric machines because it

Lowers their power efficiency

Increases their cost of manufacture

Leads to their increased weight

Produces fringing

15. Hard steel is suitable for making permanent magnets because

It has good residual magnetism

Its hysteresis loop has large area

Its mechanical strength is high

Its mechanical strength is low

16. The unit of retentivity is

Weber

Weber/sq. m

Ampere turn/metre

Ampere turn

17. A material for good magnetic memory should have

Low hysteresis loss

High permeability

Low retentivity

High retentivity

18. Those materials are well suited for making permanent magnets which haveretentivity and _coercivity.

Low, high

High, high

High, low

Low, low

19. The rate of rise of current through an inductive coil is maximum

At 63.2% of its maximum steady value

At the start of the current flow

After one time constant

Near the final maximum value of current

20. .A ferrite core has less eddy current loss than an iron core because

Ferrites have high resistance

Ferrites are magnetic

Ferrites have low permeability

Ferrites have high hysteresis

21. In a magnetic material hysteresis loss takes place primarily due to

Rapid reversals of its magnetisation

Flux density lagging behind magnetising force

Molecular friction

It high retentivity

22. The unit of reluctance is

Meter/Henry

Henry/Meter

Henry

1/Henry

Magnetic Circuit 1(TTA)

1. The unit of magnetic flux is

2.

What first name or nickname would you like us to use?

2. Those magnetic materials are best suited for making armature and transformer cores which havepermeability and___hystersis loss.

3. If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be

4. Laminated cores, in electrical machines, are used to reduce

5. When both the inductance and resistance of a coil are doubled the value of

6. Silicon steel is used in electrical machines because it has

7. Permeability in a magnetic circuit corresponds to______ in an electric circuit.

8. Conductivity is analogous to

9. The property of a material which opposes the creation of magnetic flux in it is known as

10. .Permanent magnets are normally made of

11. Conductance is analogous to

12. While comparing magnetic and electric circuits, the flux of magnetic circuit is compared with which parameter of electrical circuit ?

13. Relative permeability of vacuum is

14. Point out the wrong statement. Magnetic leakage is undesirable in electric machines because it

15. Hard steel is suitable for making permanent magnets because

16. The unit of retentivity is

17. A material for good magnetic memory should have

18. Those materials are well suited for making permanent magnets which haveretentivity and _coercivity.

19. The rate of rise of current through an inductive coil is maximum

20. .A ferrite core has less eddy current loss than an iron core because

21. In a magnetic material hysteresis loss takes place primarily due to

22. The unit of reluctance is

Magnetic Circuit 1(TTA)

1. The unit of magnetic flux is

2.

What first name or nickname would you like us to use?

2. Those magnetic materials are best suited for making armature and transformer cores which have____permeability and_______hystersis loss.

3. If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be

4. Laminated cores, in electrical machines, are used to reduce

5. When both the inductance and resistance of a coil are doubled the value of

6. Silicon steel is used in electrical machines because it has

7. Permeability in a magnetic circuit corresponds to______ in an electric circuit.

8. Conductivity is analogous to

9. The property of a material which opposes the creation of magnetic flux in it is known as

10. .Permanent magnets are normally made of

11. Conductance is analogous to

12. While comparing magnetic and electric circuits, the flux of magnetic circuit is compared with which parameter of electrical circuit ?

13. Relative permeability of vacuum is

14. Point out the wrong statement. Magnetic leakage is undesirable in electric machines because it

15. Hard steel is suitable for making permanent magnets because

16. The unit of retentivity is

17. A material for good magnetic memory should have

18. Those materials are well suited for making permanent magnets which have______retentivity and _______coercivity.

19. The rate of rise of current through an inductive coil is maximum

20. .A ferrite core has less eddy current loss than an iron core because

21. In a magnetic material hysteresis loss takes place primarily due to

22. The unit of reluctance is

2. Those magnetic materials are best suited for making armature and transformer cores which havepermeability and___hystersis loss.

18. Those materials are well suited for making permanent magnets which haveretentivity and _coercivity.