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#### Sample 2 Mark Creative Questions (New Syllabus) 2020

12th Standard EM

Reg.No. :
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Physics

Time : 01:00:00 Hrs
Total Marks : 56

Part A

28 x 2 = 56
1. What are induced dipoles.

2. An electric dipole is held in a uniform electric field.
(i) Straight the net force acting on it is zero.
(ii) The dipole is alignment parallel to the field. find the work done in rotating it through the angle of 180o.

3. Two isolated metal spheres A &B have radii R & 2R respectively and same charge q. Find which of the two spheres have greater energy density just outside the surface of the sphere.

4. Aparallel plate capacitor is charged by a battery after some time, the battery is disconnected and a dielectric slab with its thickness equal to the plate so reparation is insected between the plates. How will
(i) the capacitance of the capacitor
(ii) potential difference between the plates &
(iii) the energy stored in the capacitor the affected?
Qo - charge; Vo - potential difference,
Co - capacitance, Eo- electric field.
U0 - energy spred, before the dielectric slab is inserted.
${ Q }_{ 0 }={ C }_{ 0 }{ V }_{ 0 };\frac { { B }_{ 0 } }{ d } ;{ U }_{ 0 }=\frac { 1 }{ 2 } { C }_{ 0 }{ v }_{ 0 }^{ 2 }$

5. Gauss law is true for any closed surface, no matter what its shape or size is. Justify.

6. Will there be any effect on the potential at the point if the medium around this point is changed?

7. What is an internal resistance of cell?

8. Mention are limitation of carbon resistors.

9. What is meant by dip?

10. Where on the earth's surface is the value of
(i) angle of dip maximum
(ii) vertical component of earth's magnetic field zero

11. Explain the use of transformers in long distance transmission of electric power

12. A bar magnet is moved in the direction indicted by the arrow between two coils PQ and CD predict the directions of induced current in each coil.

13. (i) How is the speed of Electromagnetic waves in vacuum determined by the electric and magnetic fields? and
(ii) Do Electromagnetic waves carry energy and momentum?

14. Define focal length.

15. A concave lens is placed in water. WiU there be any change in focal length? Give reason

16. What are coherent sources of light?

17. The image of an object formed by a lens on the screen is not in sharp focus. Suggest a method to get a dear focussing of the image on the screen without disturbing the positions of the object, the lens or the screen.

18. What is photo emissive cell?

19. Do all the electrons that absorb a photon come out as photoelectrons?

20. The de Broglie wavelength associated with an electron accelerated through a potential difference V is λ. What will be its wavelength when the accelerating potential is increased
to 4V?

21. State the reasons. Why a chain reaction stops?

22. Give the mass number and atomic number of elements on the right-hand side of the decay process $_{ 86 }^{ 220 }{ Rn }$ ⇾ Po + He.

23. What is forward V-I characteristics?

24. What is called logical variables?

25. Define Bandwidth of transmission system.

26. What do you mean by noise in communication?

27. How does the manipulation of colours obtain in nanoscale structure?

28. What is the use of household robots?