#### Magnetism and Magnetic Effects of Electric Current Model Question Paper

12th Standard EM

Reg.No. :
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Physics

Time : 02:00:00 Hrs
Total Marks : 60
5 x 1 = 5
1. A circular coil of radius 5 cm and 50 turns carries a current of 3 ampere. The magnetic dipole moment of the coil is

(a)

1.0 amp – m2

(b)

1.2 amp – m2

(c)

0.5 amp – m2

(d)

0.8 amp – m2

2. A wire of length l carries a current I along the Y direction and magnetic field is given by $\vec { B } =\frac { \beta }{ \sqrt { 3 } } =(\hat { i } +\hat { j } +\hat { k } )T.$ The magnitude of Lorentz force acting on the wire is

(a)

$\sqrt { \frac { 2 }{ \sqrt { 3 } } } \beta Il$

(b)

$\sqrt { \frac { 1 }{ \sqrt { 3 } } } \beta Il$

(c)

$\sqrt { 2 } \beta Il$

(d)

$\sqrt { \frac { 1 }{ 2 } } \beta Il$

3. The vertical component of Earth’s magnetic field at a place is equal to the horizontal component. What is the value of angle of dip at this place?

(a)

30°

(b)

45°

(c)

60°

(d)

90°

4. The most suitable metal for permanent magnet is

(a)

copper

(b)

aluminium

(c)

steel

(d)

iron

5. When current is doubled deflection is also doubled in

(a)

moving coil galvanometer

(b)

tangent galvanometer

(c)

both of them

(d)

neither of two

6. 5 x 1 = 5
7. Diamagnetic materials

8. (1)

Steel, Alnico

9. Ferromagnetic materials

10. (2)

To find the polarity of the solenoid

11. Permanent magnets

12. (3)

Bi, Sb, Cu

13. Maxwell's right hand cork screw rule

14. (4)

Fe, Ni, Co etc.,

15. End rule

16. (5)

To find the direction of magnetic field

1 x 2 = 2
17. Assertion : If two end of a solenoid are bent and together to form a closed ring shape, it is called as toroid
Reason : Magnetic field due to a long current carrying solenoid is m
B=$\frac { \mu NI }{ L }$ =μnI (where, n=$\frac { N }{ L }$)
(a) Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) Assertion and Reason are true but Reason is the false explanation of the Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true

18. 2 x 2 = 4
19. Find the odd one out.
(a) Electric current
(b) Pole strength
(c) Magnetic flux
(d) Magnetic dipole moment

20. Find the odd one out.
(a) MRI scan
(c) Hard disc oflaptop
(d) Capacitor

21. 2 x 1 = 2
22. (I) Closed line integral means integral over a closed curve (or line), (symbol is $\oint { }$ (or) $\int _{ C }^{ }{ ] }$
(II) Right hand thumb Rule is used to determine the direction of magnetic moment
Which one is correct statement?
(a) I only
(b) Il only
(c) both are correct
(d) none of these

23. (I) The ability of the materials to retain the magnetism in them even magnetising field vanishes is called remanence or retentivity
(II) Hysterisis means 'lagging beyond' which one is incorrect statement?
Which one is correct statement?
(a) I only
(b) Il only
(c) both are correct
(d) none of these

24. 6 x 2 = 12
25. What is meant by magnetic induction?

26. Define magnetic flux.

27. State Coulomb’s inverse law.

28. State Biot-Savart’s law.

29. State Ampere’s circuital law.

30. What is meant by hysteresis?

31. 5 x 3 = 15
32. The horizontal component and vertical components of Earth’s magnetic field at a place are 0.15 G and 0.26 G respectively. Calculate the angle of dip and resultant magnetic field.

33. The repulsive force between two magnetic poles in air is 9 x 10-3 N. If the two poles are equal in strength and are separated by a distance of 10 cm, calculate the pole strength of each pole.

34. Compute the intensity of magnetisation of the bar magnet whose mass, magnetic moment and density are 200 g, 2 A m2 and 8 g cm-3, respectively.

35. Discuss Earth’s magnetic field in detail.

36. What is tangent law? Discuss in detail.

37. 3 x 5 = 15
38. An electron moving perpendicular to a uniform magnetic field 0.500 T undergoes circular motion of radius 2.80 mm. What is the speed of electron?

39. A bar magnet is placed in a uniform magnetic field whose strength is 0.8 T. Suppose the bar magnet orient at an angle 30o with the external field experiences a torque of 0.2 N m. Calculate:
(i) the magnetic moment of the magnet
(ii) the work done by an applied force in moving it from most stable configuration to the most unstable configuration and also compute the work done by the applied magnetic field in this case.

40. Calculate the magnetic field at the center of a square loop which carries a current of 1.5 A, length of each loop is 50 cm.