Haryana Board 12th Exam 2024 : Physics Most Important Question with Answers

हरियाणा बोर्ड कक्षा 12 Physics - भौतिक विज्ञान के लिए महत्वपूर्ण प्रश्न उपलब्ध हैं। हरियाणा बोर्ड 12वीं की  Physics - भौतिक विज्ञान परीक्षा 11th March, 2024 को निर्धारित है। तो यह आर्टिकल आपके लिए काफी ज्यादा महत्वपूर्ण साबित होने वाला है क्योंकि इस आर्टिकल में आपको बोर्ड परीक्षा के लिए वो ही प्रश्न दिए गए है जो बोर्ड पेपर में आने जा रहे है।

यहाँ पर हरियाणा Board क्लास 12th के Physics - भौतिक विज्ञान (Haryana Board Physics - भौतिक विज्ञान Class 12th Exam 2024 VVI Most Important Question) से संबंधित महत्वपूर्ण प्रश्न दिए गए है। महत्वपूर्ण प्रश्नों का एक संग्रह है जो बहुत ही अनुभवी शिक्षकों के द्वारा तैयार किये गए है। इसमें प्रत्येक महत्वपूर्ण प्रश्नों को छांट कर एकत्रित किया गया है, जिससे कि विद्यार्थी कम समय में अच्छे अंक प्राप्त कर सके।

 BSEH Haryana Board Class 12 Physics Important Question with Answers 

1. When the distance between two charged particles is made one-fourth, the force between them becomes:
(a) one-fourth
(b) one-third
(c) half
(d) sixteen times

Ans: (d) sixteen times

2. Ratio of magnitudes of electric force in air and water between an electron and proton is:
(a) k (dielectric constant)
(b) 1/k
(c) 1
(d) 0

Ans: (a) k (dielectric constant)

3. Which the following relation is called as current density?
(a) I/A
(b) A/I
(c) I²/A
(d) I³/A²

Ans: (a) I/A

4. A circuit has a resistance of 12 ohm and an impedance 15 ohm. The power factor of the circuit will be
(a) 0.8
(b) 0.4
(c) 1.25
(d) 0.125

Ans: (a) 0.8

5. The magnitude of saturation photoelectric current depends upon
(a) frequency
(b) intensity
(c) work function
(d) stopping potential

Ans: (b) intensity

6. CGS unit of electric charge is
(a) Coulomb
(b) Joule
(c) Faraday
(d) Stat Coulomb

Ans: (d) stat coulomb

7. A thin convex lens of focal length 30 cm is placed in contact with a thin concave lens of focal length 20 cm. What is the focal length of the combination?
(a) +50 cm
(b) –60 cm
(c) +10 cm
(d) –10 cm

Ans: (b) –60 cm

8. Hole is—
(a) an anti particle of electron
(b) a vacancy created when an electron leaves a covalent bond
(c) absence of free electrons
(d) an artificially created particle

Ans: (b) a vacancy created when an electron leaves a covalent bond.

9. In a p-type silicon, which of the following statement is true:
(a) Electrons are majority carriers and trivalent atoms are the dopants.
(b) Electrons are minority carriers and pentavalent atoms are the dopants.
(c) Holes are minority carriers and pentavalent atoms are the dopants.
(d) Holes are majority carriers and trivalent atoms are the dopants.

Ans: (d) Holes are majority carriers and trivalent atoms are the dopants.

10. Taking the Bohr radius as a₀ = 53 pm, the radius of Li⁺⁺ ion in its ground state, on the basis of Bohr's model, will be about—
(a) 53 pm
(b) 27 pm
(c) 18 pm
(d) 13 pm

Ans: (c) 18 pm.

11. An electric dipole placed in a non-uniform electric field can experience
(a) a force but not a torque
(b) a torque but not a force
(c) always a force and a torque
(d) neither a force nor a torque

Ans: (c) always a force and a torque

12. If the net electric flux through a closed surface is zero, then we can infer–
(a) no net charge is enclosed by the surface.
(b) uniform electric field exists within the surface.
(c) electric potential varies from point to point inside the surface.
(d) charge is present inside the surface.

Ans: (a) no net charge is enclosed by the surface

13. Kirchoff’s first rule at a junction in an electrical network, deals with conservation of:
(a) energy
(b) charge
(c) momentum
(d) both energy and charge

Ans: (b) charge

14. The resistance of a metal wire increases with increasing temperature on account of
(a) decrease in free electron density
(b) decrease in relaxation time
(c) increase in mean free paths
(d) increase in the mass of electron

Ans: (b) decrease in relaxation time

15. The magnetic dipole moment of a current carrying coil does not depend upon
(a) number of turns of the coil
(b) cross-sectional area of the coil
(c) current flowing in the coil
(d) material of the turns of the coil

Ans: (d) material of the turns of the coil

16. For a glass prism, the angle of minimum deviation will be smallest for the light of:
(a) red colour
(b) blue colour
(c) yellow colour
(d) green colour

Ans: (a) red colour

17. A cell of internal resistance r connected across an external resistance R can supply maximum current when
(a) R = r
(b) R > r
(c) R = 2/r
(d) R = 0

Ans: (d) R = 0

18. In a current carrying conductor the ratio of electric field and the current density at a point is called
(a) Resistivity
(b) Conductivity
(c) Resistance
(d) Mobility

Ans: (a) Resistivity

19. Above curie temperature, a
(a) ferromagnetic material becomes diamagnetic
(b) ferromagnetic material becomes paramagnetic
(c) paramagnetic material becomes ferromagnetic
(d) paramagnetic material becomes diamagnetic

Ans: (b) ferromagnetic material becomes paramagnetic

20. Displacement current exists only when
(a) electric field is changing
(b) magnetic field is changing
(c) electric field is not changing
(d) magnetic field is not changing

Ans: (a) electric field is changing

21. What is displacement current? How is it different from a conduction?

Ans: Displacement current is due to changing electric field.

Conduction current is due to flow of electrons in the circuit.

22. Write Farday's laws of Electromagnetic induction.

Ans: Faraday's 1st law: Whenever there is a change in the magnetic flux linked with the circuit changes an e.m.f is induced in it. It lasts so long as the change in the flux continues.

Faraday's 2nd law: The rate of change of magnetic flux linked with a circuit is directly proportional to emf. induced.

23. Define magnetic dipole moment and give its S.I. unit. Also mention the direction of magnetic dipole moment.

Ans: Magnetic dipole moment is the product of strength of either pole (m) and the magnetic length (2l) of the magnet. 

It's S.I. unit is joule/tesla or Am²

The direction of magnetic dipole moment is from South to North pole of the magnet.

24. Define drift velocity? Establish the relation between current and drift velocity.

Ans: Drift velocity is defined as the average velocity with which the free electrons get drifted towards the positive end of the conductor under the influence of an
external electric field.

Relation b/w current and drift velocity 

If n is the number density of electrons then total number of free electrons in the conductors = A l n

If e is charge on each electron then total charge q = Al ne ...(1)

Time taken by es to cross the conductors

25. State and prove Gauss's law in Electrostatics.

Ans: Gauss's Theorem: The surface integral of electric field over a closed path is equal to 1/∈₀ times the total charge enclosed by surface. 

26. What do you mean by electromagnetic waves? Give two uses of gamma rays.

Ans: Electromagnetic waves are the waves in which electric field and magnetic field vectors are perpendicular to each other as well as perpendicular to direction of
propagation. 

Two uses of gamma rays—
1. γ-rays are used in the treatment of cancer and tumours.
2. These are used to produce nuclear reactions.

27. What is nuclear binding energy? Draw a curve between mass number and binding energy per nucleon.

Ans: Binding energy of a nucleus is the energy with which nucleons are bound in the nucleus. 

27. What is quantisation of charge? Why it has no practical consequence at macroscopic level?

Ans: Total charge present on a body is fixed. Total charge is integral multiple of smallest unit of charge i.e. electronic charge.

                                            Q = ne

At macroscopic level total charge present on a body is much larger than the charge on an electron.
Granary nature of charge on electron vanishes. So it has no practical consequence at macroscopic level.

28. State and prove Ampere’s circuital law.

Ans: Line integral of the magnetic field over a closed path is equal to µ₀ times the net current (I) passing through the enclosed path.

Proof: Consider a long thin straight conductor XY, carrying current as shown in fig.

Mag. field as P at a distance r is given by

29. Explain refraction of light through prism. Find out the formula for calculating the refractive index of the material of prism

Ans: 

30. Which of the following electromagnetic waves has (a) minimum wavelength (b) minimum frequency? Write one use of each of these two waves. Infrared waves, microwaves, γ-rays and X-rays.

Ans: (a) minimum wavelength : γ-rays
(b) minimum frequency : Microwaves
γ-rays are used to treat cancer.
Microwaves are used in communication

31.  An object is kept 20 cm in front of a concave mirror of radius of curvature 60 cm. Find the nature and position of the image formed.

Ans: Values of f and u with sign convention
Nature of image
Position of image 

32. What are electric field lines? Draw these for a point charges +Q and –Q.

Ans: Electric field lines are imaginary lines, can be straight or curved, tangent to it at any point gives the direction of electric field.

33. Draw a phasor diagram when a pure capacitor is connected to an alternating (a.c.) source and show that there is a phase difference of 90° between the voltage and current.

Ans: 

34. Discuss the variation of photoelectric current with collector plate potential for different frequency of incident radiation.

Ans: 

* If we take radiations of different frequencies and same intensity then saturated current is same for all radiations but their stopping potential is different.

* Greater is the frequency of incident radiation, higher is the value of kinetic energy of photoelectron and hence more will be the stopping potential.

35. (i) Define the SI unit of power of a lens.
(ii) A plano convex lens made of glass of refractive index 1.5. The radius of curvature of the convex surface is 25 cm. Calculate the focal length of the lens.

Ans: 

36. Explain the limitations of ohm's law?

Ans: 

37. Draw Schematic diagram of a reflecting telescope (cassegrain). Write its two advantages over refracting telescope.

Ans: 

38. How energy bands (conduction band and valance band) are formed in solids?

Ans: 

The process of splitting of energy levels can be understood by considering the different situations.

(i) When r = d – No modification of energy levels.

(ii) When r = c – Interaction b/w outermost shell electrons of neighbouring Si atoms increases and energy gap b/w 2N – 3s levels and 6N – 3p levels goes on decreasing.

(iii) When b < r < c – Instead of single 3s and 3p level, we get large no. of closely packed level.

(iv) When r = b > a – The energy gap b/w 3s and 3p levels completely disappears and all the 8N levels are continuously distributed. One can say that 4N levels are filled and 4N levels are empty.

(v) When r = a – 4N filled levels get separated from 4N empty levels. 4N filled level form a band called valance band and 4N empty levels form a band called conduction band.

39. Calculate the current in each branch of the network show in fig.

Ans: 

40. On the basis of energy level diagram differentiate between conductors, semiconductors and insulators.

Ans: Full-wave rectifier  

During +ve half cycle diode D₁ is forward biased and diode D₂ is reverse biased. The forward current flows due to D₁ . During –ve half cycle, diode D₁ is reverse biased and diode D₂ is forward biased. The forward current flows due to D₂ . The output waveforms is shown in figure.

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Haryana Board Class 12th Physics 2024 : हरियाणा बोर्ड कक्षा 12 भौतिक विज्ञान प्रैक्टिस पेपर, पीडीएफ डाउनलोड करें

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