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#### Magnetism and Magnetic Effects of Electric Current One Mark Questions

12th Standard EM

Reg.No. :
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Physics

Time : 00:30:00 Hrs
Total Marks : 15
10 x 1 = 10
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 thin insulated wire forms a plane spiral of N = 100 tight turns carrying a current I = 8 m A (milli ampere). The radii of inside and outside turns are a = 50 mm and b = 100 mm respectively.
The magnetic induction at the center of the spiral is

(a)

$5\mu T$

(b)

$7\mu T$

(c)

$8\mu T$

(d)

$10\mu T$

3. 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)

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

4. 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°

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. An electron of mass 0.90 x 10-30kg under the action of a magnetic field moves in a circle of 2cm radius at a speed of 3 x 106 m/s if a proton of mass 1.8 x 10-27 kg was to move in a circle of the same radius in the same magnetic field, then its speed will be

(a)

3.0 x 106 m/s

(b)

1.5 x 103 m/s

(c)

6.0 x 104 m/s

(d)

cannot be estimated from the same data

7. Cyclotron is used to

(a)

accelerate charged particles or ions to low voltages

(b)

decelerate charged particles or ions to high voltages

(c)

accelerate charged particles or ions to high energies

(d)

accelerate charged particles or ions to high voltages

8. Joule's law is verified using

(a)

Joule's calorimeter

(b)

Joule's voltmeter

(c)

Joule's galvanometer

(d)

thermometer

9. Thermopile is used to

(a)

measure temperature

(b)

measure current

(c)

(d)

measure pressure

10. Which one of the following is correct. According to Biot-Savart law, the magnetic induction is directly proportional to

(a)

Square of the current

(b)

Square root of the current

(c)

Length of the current element

(d)

Square of the distance

11. 5 x 1 = 5
12. Diamagnetic materials

13. (1)

Fe, Ni, Co etc.,

14. Paramagbetic materials

15. (2)

Steel, Alnico

16. Ferromagnetic materials

17. (3)

Bi, Sb, Cu

18. Permanent magnets

19. (4)

Pt, Cr, Mn

20. Right hand thumb rule

21. (5)

Applied for circular coil carrying current