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

12th Standard EM

Reg.No. :
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Physics

Time : 00:45:00 Hrs
Total Marks : 25
25 x 1 = 25
1. The most suitable metal for permanent magnet is

(a)

copper

(b)

aluminium

(c)

steel

(d)

iron

2. Direction of magnetic force on a positive charge moving in a magnetic field is given by

(a)

thumb rule

(b)

left hand rule

(c)

right hand rule

(d)

cork screw rule

3. Lorentz force generally refers to force experienced by a charge due to combined action of

(a)

magnetic fields

(b)

electric fields

(c)

electric, magnetic & gravitational fields

(d)

electric and magnetic fields

4. Two thin long parallel wires separated by a distancea' are carrying current I amp each. The magnitude of the force per unit length excited by one wire on the other is

(a)

$\frac { { \mu }_{ 0 }{ I }^{ 2 } }{ a^{ 2 } }$

(b)

$\frac { { \mu }_{ 0 }{ I }^{ 2 } }{ 2\pi a }$

(c)

$\frac { { \mu }_{ 0 }{ I } }{ 2\pi a }$

(d)

$\frac { { \mu }_{ 0 }{ I } }{ 2\pi a^{ 2 } }$

5. At a given place the horizontal component of earth's field is 0.2 x 10-4 Tesla. If a vertical wire carries a current of 30A upward, what is the magnitude and direction of the force on 1m of wire?

(a)

6 East to West

(b)

6 x 10-2 East to West

(c)

6 x 10-3 East to West

(d)

6 x 10-4 East to West

6. Which one of the following pair of particles move with same velocity along the same circular path in a uniform magnetic field?

(a)

electron, proton

(b)

proton, deutron

(c)

proton, alpha particle

(d)

deutron, alpha particle

7. In a T.G. experiment, for two different values of current, the deflections are 45° and 30° respectively, then the ratio of the current is

(a)

2 : 3

(b)

3 : 2

(c)

$\sqrt{3}$ : 1

(d)

1 : $\sqrt{3}$

8. The Tangent Galvanometer is more sensitive for this angle of deflection

(a)

3.14 radian

(b)

45 radian

(c)

0.785 radian

(d)

1.57 radian

9. The magnitude and direction of magnetic Lorentz force

(a)

$\vec { F } =\vec { v } \times \vec { B }$

(b)

$\vec { F } =q/(\vec { v } \times \vec { B } )$

(c)

$\vec { F } =q(\vec { v } \times \vec { B } )$

(d)

$\vec { F } =v(\vec { v } \times \vec { B } )$

10. The angular. momentum of an electron revolving in second order (n = 2) is

(a)

6.6 x 10-34 Js

(b)

3.3 x 10-34 Js

(c)

2.1 x 10-34 Js

(d)

9.27 x 10-34 Js

11. The magnetic declination for chennai is _______

(a)

-1° 5'

(b)

1°8'

(c)

-1°8'

(d)

1°5'

12. A wire of length 1 m carrying a current of 2 A is placed inside a field of magnetic induction 20 T such that it makes an angle of 30° with the direction of the field. The force experienced by the wire is

(a)

40N

(b)

10$\sqrt { 3 }$ N

(c)

20N

(d)

20$\sqrt { 3 }$N

13. To convert a galvanometer into an ammeter we connect which one of the following to the galvanometer?

(a)

a low resistance in series

(b)

a high resistance in series

(c)

a low resistance in parallel

(d)

a high resistance in parallel

14. The resistance of the filament of a 110 W, 220 V electric bulb is,

(a)

440 Ω

(b)

220 Ω

(c)

484 Ω

(d)

848 Ω

15. These are behaving like thermistor

(a)

insulators and conductors

(b)

semiconductors and conductors

(c)

insulators and semiconductors

(d)

conductors and alloys

16. Which of the following principle is used in a thermopile?

(a)

Thomson effect

(b)

Peltier effect

(c)

Seebeck effect

(d)

Joules effect

17. In a thermocouple, temperature of the cold junction is 20°C, the inversion of temperature is 600°C, then neutral temperature is

(a)

310°C

(b)

320°C

(c)

300°C

(d)

315°C

18. A deutron and an alpha particle move in a magnetic field along the same circular path, then the ratio of their velocities is _______

(a)

1:2

(b)

2:1

(c)

4:1

(d)

1:1

19. If a deutron and an alpha particle move perpendicular to a uniform magnetic field with same velocity, then the ratio of the radii of their path is ______

(a)

1:1

(b)

1:2

(c)

2:1

(d)

4:1

20. The period T of circular motion of a particle of mass m and charge q moving inside a uniform magnetic field of induction B is given by ______

(a)

Bq = Tm

(b)

T=$\frac { Bq }{ 2\pi m }$

(c)

BqT = 2πm

(d)

TBM=2πq

21. The current through a solenoid of length 0.5 m with 400 turns produces a magnetic field 10-3 tesla. The current is _______

(a)

2A

(b)

20

(c)

1A

(d)

0.5 mA

22. The force between two parallel wires carrying current is _______

(a)

F=$\frac { { \mu }_{ 0 } }{ 2\pi } \frac { { I }_{ 1 }{ I }_{ 2 }l }{ a }$

(b)

F=$\frac { { \mu }_{ 0 } }{ 2\pi } \frac { { I }_{ 1 }{ I }_{ 2 }l }{ al }$

(c)

F=$\frac { { \mu }_{ 0 } }{ 2\pi } \frac { { I }_{ 1 }{ I }_{ 2 } }{ a.l }$

(d)

F=$\frac { { \mu }_{ 0 } }{ 2\pi } { I }_{ 1 }{ I }_{ 2 }\frac { l }{ a }$

23. No current flows between two charged particles when connected if they have same ______

(a)

capcity

(b)

potential

(c)

charge

(d)

none of these

24. Torque acting on a coil is maximum when the coil is ______

(a)

parallel to the magnetic field

(b)

perpendicular to the magnetic field

(c)

at an angle of 45° to the magnetic field

(d)

at any position in a uniform magnetic field

25. If a current 0.5mA produces a deflection of 156°, then the galvanometer constant is about, ______

(a)

0.33 A rad-1

(b)

2 A rad-1

(c)

3 A rad-1

(d)

7.5 A rad-1