#### 12th Standard Physics English Medium Reduced Syllabus Important Questions - 2021 Part - 2

12th Standard

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Physics

Time : 01:00:00 Hrs
Total Marks : 160

Multiple Choice Questions

10 x 1 = 10
1. The internal resistance of a 2.1 V cell which gives a current of 0.2 A through a resistance of 10 Ω is

(a)

0.2 Ω

(b)

0.5 Ω

(c)

0.8 Ω

(d)

1.0 Ω

2. The emf of a battery is 3 volts and internal resistance 0.125 $\Omega$ . The difference of potential
at the terminal of battery when connected across an external resistance of 1 $\Omega$ is

(a)

1.67 V

(b)

0.67 V

(c)

2.67 V

(d)

3.67 V

3. Peltier effect is the converse of

(a)

Joule effect

(b)

Raman effect

(c)

Thomson effect

(d)

Seebeck effect

4. Kirchoff's II law isa consequence of conservation of________

(a)

eharges

(b)

momentum

(c)

energy

(d)

power

5. 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

6. The direction of the magnetic field due to a solenoid is given by

(a)

Amperes circuital law

(b)

Biot-Savart law

(c)

Right hand palm rule

(d)

Flemings right hand law

7. The word 'Magnetism' was derived from Iron are _________

(a)

Fe3O2

(b)

Fe3O3

(c)

Fe3O4

(d)

Fe2O3

8. The necessary magnetic field for a low power a.c generator is produced by _________

(a)

electric coil

(b)

permanent magnets

(c)

electromagnets

(d)

batteries

9. Internal frames are _______ frames.

(a)

variable

(b)

accelerated

(c)

unaccelerated

(d)

varying

10. When an electric field is applied to an atom each of the spectral lines split into several lines. This effect is known as

(a)

Zeeman effect

(b)

Stark effect

(c)

Raman effect

(d)

Seebeck effect

11. 2 Marks

15 x 2 = 30
12. What is electric power and electric energy?

13. What do you mean by internal resistance of a cell?

14. What is Seebeck effect?

15. Define Ampere.

16. What is an internal resistance of cell?

17. State Biot-Savart’s law.

18. State Ampere’s circuital law.

19. What is Geomagnetism?

20. What are the properties required to make Permanent magnets?

21. Give any one definition of power factor.

22. What is meant by power transmission?

23. What is the value of power if the circuit is
(i) purely resistive
(ii) Purely inductive or capacitive.

24. The motion of copper plate is damped when it is allowed to oscillate between the two poles of a magnet what is the cause of this damping?

25. It is possible for two lenses to produce zero power?

26. Define internal field emission or field ionization.

27. 3 Marks

15 x 3 = 45
28. What are carbon resistors? What does the colour indicates?

29. Derive a relation between internal resisance and emf of a cell

30. In a circuit containing internal resistance r. Find the power delivered

31. Find the magnetic field due to a long straight conductor using Ampere’s circuital law.

32. What are the types of magnets? Give example.

33. Tabulate the difference between Coulomb's law and Biot-Savort's law.

34. Establish the fact that the relative motion between the coil and the magnet induces an emf in the coil of a closed circuit.

35. Find out the phase relationship between voltage and current in a pure inductive circuit.

36. Obtain an expression for average power of AC over a cycle. Discuss its special cases

37. What is the phase different between
(i) the voltage across L and C in a LCR circuit connected to an a.c source
(ii) applied a.c voltage and current in LCR circuit at resonance.

38. How does Ampere - Maxwell law expalain the flux of current trough a capacitor when it is being charged by a battery? write the expression for the displacement current in terms of the rate of change of electric flux.

39. What is dispersion? Obtain the equation for dispersive power of a medium.

40. With respect to power generation, what are the relative advantages and disadvantages of fusion type and Fission type reactors?

41. Obtain the equation for resolving power of optical instrument.

42. Draw the circuit diagram' of a half wave rectifier and explain its working

43. 5 Marks

15 x 5 = 75
44. A battery has an emf of 12 V and connected to a resistor of 3 Ω. The current in the circuit is 3.93 A. Calculate (a) terminal voltage and the internal resistance of the battery (b) power delivered by the battery and power delivered to the resistor

45. The following figure shows a complex network of conductors which can be divided into two closed loops like ACE and ABC. Apply Kirchoff’s voltage rule.

46. Explain what is (i) Thomson effect, (ii) Positive Thomson effect, (iii) Negative effect.

47. Use Kirchhoff's laws (rules) to determine the potential difference between points A and D when no current flows in the arm BE of the electric network shown in the figure. below

48. 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?

49. Explain the Motion of a charged particle in a uniform magnetic field.

50. Two air core solenoids have the same length of 80 cm and same cross–sectional area 5 cm2. Find the mutual inductance between them if the number of turns in the first coil is 1200 turns and that in the second coil is 400 turns.

51. The solenoids S1 and S2 are wound on an iron-core of relative permeability 900. The area of their cross-section and their length are the same and are 4 cm2 and 0.04 m respectively. If the number of turns in S1 is 200 and that in S2 is 800, calculate the mutual inductance between the coils. The current in solenoid 1 is increased form 2A to 8A in 0.04 second. Calculate the induced emf in solenoid 2.

52. Explain the mutual induction between two long solenoids. Obtain an expression for the mutual inductance.

53. The current flowing in two coils of self inductance L1 = 20mH and L2 = 15mH are increasing at the same rate. If the power supplied to the two coils are equal. Find the ratio of
(i) induced emf
(ii) induced current and
(iii) the energies stored in the two coils at a given instant .

54. Show how to generalize Ampere's circuital law to include the term due to displacement current?

55. (i) Define the term 'intensity of radiation' in photon picture.
(ii) Plotagraph showing the variation of photo current vs collector potential for three
different intensities I1 > I2> I3 two of which (I1 and I2) have the same frequency v and the third has frequency v1 > v.
(iii) Explain the nature of the curves on the basis of Einstein's equation.

56. For photo electronic effect in sodium, the figure shows the plot of cut-off voltage versus frequency of incident radiation. Calculate
(i) threshold frequency
(ii) work function for sodium.

57. Four silicon diodes and a 10 Ω resistor are connected as shown in figure below. Each diode has a resistance of 1Ω. Find the current flows through the 18Ω resistor.

58. Explain current transfer characteristics.