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#### Sample 1 Mark Creative Questions (New Syllabus) 2020

12th Standard EM

Reg.No. :
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Physics

Time : 00:30:00 Hrs
Total Marks : 35

Part A

35 x 1 = 35
1. The relative permittivity of water is _______.

(a)

εr= 70

(b)

εr=75

(c)

εr=80

(d)

εr=85

2. The force experienced by a unit charge is called

(a)

Electric potential

(b)

Electric flux

(c)

Electric field

(d)

Static electricity

3. Two charges are kept at a distance in air what should be the relative permittivity of the medium in which the two charges should be kept at the same distance so that they experience half of the force which they experienced in air?

(a)

$\frac{1}{2}$

(b)

$\frac{1}{0.2}$

(c)

2

(d)

0.2

4. For continuous charge distributions, _____ methods can be used.

(a)

integration

(b)

differentiation

(c)

multiplication

(d)

5. Two charged bodies of charges +q, -3q are brought in contact and separated. The charges prossed by each body after separation.

(a)

-q,-q

(b)

+q,-2q

(c)

-q, +3q

(d)

q, q

6. If the specific resistance of a potentiometer wire is 10-7 Om and current flowing through it . is 0.1 amp, cross - sectional area of wire is 10-6 m2, then potential gradient will be

(a)

10-2 v/m

(b)

10-4 v/m

(c)

10-6 v/m

(d)

10-8v/m

7. A bird sitting on an insulated wire carrying a current feels quite safe because

(a)

the bird is a non-conductor of electricity

(b)

resistance of the bird is very large

(c)

there is a large potential difference between bird and wire

(d)

there is no potential difference between bird and wire

8. Which material is having a small value of temperature coefficient of resistance?

(a)

copper

(b)

constantan or manganin

(c)

nichrome

(d)

both b & c

9. Thermo electric generators are used in power plants to convert_________ into electricity ..

(a)

light energy

(b)

waste heat

(c)

sound energy

(d)

hydro energy

10. In a carbon resistor, the third ring represents___________

(a)

powers of zeros

(b)

powers of ten

(c)

ten

(d)

infinity

11. The most suitable metal for permanent magnet is

(a)

copper

(b)

aluminium

(c)

steel

(d)

iron

12. Graph of force per unit length between long parallel current carrying conductors, and the distance between them is

(a)

straight line

(b)

parabola

(c)

ellipse

(d)

rectangular hyperbola

13. A 110 W, 220 V bulb draws a current

(a)

2 A

(b)

440 A

(c)

0.5 A

(d)

5.5 A

14. In a tangent galvanometer a current 1A, produces deflection of 30° the current required to produce a deflection of 60° is

(a)

3A

(b)

2A

(c)

$\sqrt { 2 }$

(d)

$\frac { 1 }{ \sqrt { 3 } }$A

15. 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

16. An α-particle enters a magnetic field of 1T with a velocity 106 m/s in a direction perpendicular to the field. The force on α-particle is

(a)

1.6 x 10-13N

(b)

6.4  x 10-13N

(c)

4.8  x 10-13N

(d)

3.2  x 10-13N

17. The elements having Thomson positive effect are ________

(a)

Sb, Hg, Zn

(b)

Ag, Hg, Cd

(c)

Zn, Cd, Sb

(d)

Cd, Pt, Ag

18. 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

19. The magnitude of the induced emf in a conductor depends on the

(a)

flux density of the magnetic field

(b)

amount of flux cut

(c)

(d)

rate of change of flux

20. Flux loss can be minimized using ________ core.

(a)

laminated

(b)

shell-type

(c)

perforated

(d)

sheet-type

21. The electric and magnetic field of an EM wave are

(a)

in phase and perpendicular to each other

(b)

in phase and parallel to each other

(c)

in opposite phase and perpendicular to each other

(d)

in opposite phase and parallel to each other

22. A red flower seen in the light of mercury vapour lamp through a green filter will appear

(a)

black

(b)

red

(c)

violet

(d)

white

23. ________ radiations are used to study atomic structure.

(a)

UV

(b)

IR

(c)

X-rays

(d)

Gamma

24. A ray of light is incidenting normally on a .plane mirror. The angle of reflection will be

(a)

(b)

90°

(c)

will not be reflected

(d)

None of these

25. A diminished virtual image can be formed only in

(a)

Plane mirror parabolic mirror

(b)

A concave mirror

(c)

A convex mirror

(d)

concave

26. A point object is moving on the principal axis of a concave mirror of focal length 24 cm towards the mirror. When it is' at a distance of 60 cm from the mirror, its velocity is 9 cm/ sec. what is the velocity of the image at that instant?

(a)

5 cm/see toward the mirror

(b)

4 cm/see towards the mirror

(c)

4 cm/see away from the mirror

(d)

9 cm/see away from the mirror

27. Stopping potential of emitted photo electrons is given by (where ф =hv0)

(a)

$\frac { hv-{ \phi }_{ 0 } }{ e }$

(b)

hv-ф

(c)

$\frac { hv }{ e }$

(d)

$\frac { hv+{ \phi }_{ 0 } }{ e }$

28. When the momentum of a particle increases) the de Broglie wavelength

(a)

increases

(b)

decreases

(c)

does not change

(d)

infinity

29. ______ theory explains photo electric effect.

(a)

Electromagnetic

(b)

Quantum

(c)

Wave

(d)

Corpuscular

30. An oil drop carrying a charge q has a mass m kg. It is falling freely in air with terminal speed v. The electric field required to make the drop move upwards with the same speed is

(a)

$\frac{mg}{q}$

(b)

$\frac{2mg}{q}$

(c)

$\frac{mgv}{q^2}$

(d)

$\frac{2mgv}{q}$

31. The ground-state energy of hydrogen atom is ____________ eV

(a)

-13.6

(b)

-18.7

(c)

18.6

(d)

$\frac{1}{13.6}$

32. The behaviour of Ge as semi-conductor is due to width of:

(a)

conduction band being large

(b)

forbidden band being small

(c)

conduction band being small

(d)

forbidden band being small and narrow

33. The cause of potential barrier in a p-n diode is

(a)

depletion of negative charges near the junction

(b)

concentration of positive charges near the junction

(c)

depletion of positive charges near the junction

(d)

concentration of positive and negative charges near the junction

34. The radio waves of frequency 30 MHz to 300 MHz belong to

(a)

high frequency band

(b)

very high frequency band

(c)

ultra high frequency band

(d)

super high frequency band

35. Muscle wires can contract by _________ when electric current is passed through them

(a)

5%

(b)

7%

(c)

25%

(d)

50%