JAC 12th Physics Most Important Question 2024 [Download PDF]

झारखंड बोर्ड ने 12वीं कक्षा के बोर्ड परीक्षा के लिए बहुविकल्पी प्रश्न उत्तर जारी किया है। इस लेख में आपको Physics के बहुवैकल्पिक प्रश्न उत्तर मिलेंगे। अगर आपको सभी विषयों के बहुवैकल्पिक प्रश्न उत्तर चाहिए तो हमारी वेबसाइट www.vidyastudy.com से जुड़े रहें। बहुवैकल्पिक प्रश्न उत्तर की जानकारी आपको इस वेबसाइट पर सबसे पहले मिलेगी। अगर आपने अभी तक बहुवैकल्पिक प्रश्न उत्तर डाउनलोड नहीं किया है, तो नीचे दिए गए लिंक पर जाकर वहां से डाउनलोड कर सकते हैं।

इस लेख में हम 12वीं कक्षा के विषय – Physics के उत्तर (Solution/Answer) को देखेंगे। आपको यह भी पता चलेगा कि प्रश्न पेपर कैसे प्रस्तुत किए जाते हैं और आपके परीक्षा में प्रश्न कैसे होंगे, जिसमें विषयवार प्रश्न (ऑब्जेक्टिव प्रश्न) नीचे दिए गए हैं।

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1. Dimensional formula of ε0 is

(1) [M¹L²T^-4A^-2]
(2) [M^-1L^-3T⁴A²]
(3) [M¹L³T^-4A^-2]
(4) [M^-1L^-2T^-4A²]

Ans: (2)

2. According to Gauss’ Law of electrostatics

(1) ϕ_E=ε₀/2
(2) ϕ_E=q/ε₀
(3) ϕ_E=qε₀
(4) ϕ_E=1/qε₀

Ans: (2)

3. The number of electrons for two coulombs of charge is:

(1) 1.25×10¹⁸
(2) 1.25×10¹⁹
(3) 1.25×10²¹
(4) 1.25×10²³

Ans: (2)

4. If the distance between two plates of a parallel plate capacitor is halved, its capacity:

(1) increases 2 times
(2) decreases 2 times
(3) increases 4 times.
(4) decreases 4 times

Ans: (1)

5. The electric potential at a point inside a charged spherical shell is:

(1) zero
(2) constant
(3) variable
(4) maximum

Ans: (2)

6. The electric field and the potential of an electric dipole vary with distance r as

(1) 1/r and 1/r²
(2) 1/r² and 1/r
(3) 1/r² and 1/r³
(4) 1/r³ and 1/r²

Ans: (4)

7. Kirchhoff’s loop rule is a direct consequence of law of conservation of:

(1) Charge
(2) Momentum
(3) Angular momentum
(4) Energy

Ans: (4)

8. A charged particle has drift velocity 4.2×10-ms” in electric field of 2.1×10 V m. Its mobility is

(1) 0.5×10⁶ m²V^-1s^-1
(2) 2×10⁶ m²V^-1s^-1
(3) 0.5×10^-6 m²V^-1s^-1
(4) 2×10^-6 m²V^-1s^-1

Ans: (2)

9. The magnetic force on a current carrying conductor of length in an external magnetic field B is given by:

Ans: (3)

10. A circular coil of radius 10 cm having 100 turns carries a current of 3.2 A. The magnetic field at the centre of the coil is

(1) 2.01×10^-3 T
(2) 5.64×10^-3 T
(3) 2.64×10^-4 T
(4) 5.64×10^-4 T

Ans: (1)

11. Which of the following is not correct about the magnetic field lines?

(1) The magnetic field lines of a magnet form continuous closed loops
(2) The tangent to the field lines at a given point represents the direction of the net magnetic field at that point
(3) The larger the number of field lines crossing per unit area, the stronger is the magnitude of the magnetic field B
(4) The magnetic field lines may intersect each other in certain conditions

Ans: (4)

12. The magnetic lines of force inside a bar magnet:

(1) are from N-pole to S-pole of the magnet
(2) are from S-pole to N-pole of the magnet
(3) depends on area of cross-section of bar magnet
(4) do not exist

Ans: (2)

13. The vertical component of earth’s magnetic field at a place is √3 times the horizontal component. The value of angle of dip at this place is:

(1) 30
(3) 60°
(2) 45
(4) 90°

Ans: (3)

14. The magnetic flux linked with a coil of N turns of area of cross-section A held with its plane parallel to the field B is:

(1) NAB
(2) NAB/2
(3) NAB/4
(4) zero

Ans: (4)

15. Direction of current induced in a wire moving in a magnetic field is found using:

(1) Fleming’s left-hand rule
(2) Fleming’s right-hand rule
(3) Ampere’s rule
(4) none of these

Ans: (2)

16. If number of turns in primary and secondary coils is Increased to two times each, the mutual inductance

(1) becomes 4 times
(2) becomes 2 times
(3) becomes 1/4 time
(4) remains unchanged

Ans: (1)

17. A 100 resistor is connected to a 220 V, 50 Hz ac supply. The r.m.s. value of current in the circuit is

(1) 1.56 A
(2) 1.56 mA
(3) 2.2 A
(4) 2.2 mA

Ans: (3)

18. In series LCR circuit, the phase angle between supply voltage and current is:

Ans: (1)

19. Which of the following electromagnetic waves has the greatest frequency?

(1) Radio waves
(3) Infrared rays
(2) Ultraviolet rays
(4) γ-rays

Ans: (4)

20. …………… is used for photography in fog.

(1) Polaroid
(2) Infrared
(3) Ultraviolet
(4) X-rays

Ans: (2)

21. A virtual image larger than the object is formed in:

(1) Convex mirror
(3) Plane mirror
(2) Concave mirror
(4) None of these

Ans: (2)

22. The image formed by a simple microscope is:

(1) imaginary and erect
(2) imaginary and inverted
(3) real and erect
(4) real and inverted

Ans: (1)

23. With increase in wavelength, the value of refractive index

(1) increases
(2) decreases
(3) remains unchanged
(4) none of these

Ans: (2)

24. The concept of secondary wavelets was given by:

(1) Fresnel
(2) Newton
(3) Huygens
(4) Maxwell

Ans: (3)

25. Two waves whose intensities are in the ratio 9:1 produce interference. The ratio of maximum and minimum intensities will be

(1) 10:8
(2) 9:1
(3) 4:1
(4) 2:1

Ans: (3)

26. A ray of light is incident on a glass plate at an angle of 60°. If the reflected and refracted rays are mutually perpendicular, then the refractive index of the material is

(1) √3/2
(2) √3
(3) 1/√3
(4) 1/2

Ans: (2)

27. Which of the following metals has minimum work function?

(1) Iron
(2) Copper
(3) Barium
(4) Sodium

Ans: (4)

28. The ratio of de-Broglie wavelengths associated with two electrons accelerated by 25 V and 36 V is

(1) 25/36
(2) 36/25
(3) 5/6
(4) 6/5

Ans: (4)

29. The Bohr model of atoms:

(1) assumes that the angular momentum of electrons is quantized
(2) uses Einstein’s photoelectric equation
(3) predicts continuous emission spectra for atoms
(4) predicts the same emission spectra for all types of atoms

Ans: (1)

30. S.I. unit of Rydberg constant R is:

(1) m
(2) m²
(3) m^-1
(4) m^-2

Ans: (3)

31. Mean life of a radioactive sample is 100 second (s). Then its half-life is:

(1) 6.93 s
(2) 0.693 s
(3) 69.3 s
(4) 100 s

Ans: (3)

32. In ₈₈Ra²²⁶ nucleus, there are

(1) 138 protons and 88 neutrons
(2) 138 neutrons and 88 protons
(3) 226 protons and 88 electrons
(4) 226 neutrons and 138 electrons

Ans: (2)

33. Zener diode functions in:

(1) forward biased condition
(2) reverse biased condition
(3) both forward and reverse biased condition.
(4) none of these

Ans: (2)

34. As temperature increases the resistance of a semiconductor:

(1) increases
(2) decreases
(3) remains constant
(4) none of these

Ans: (2)

35. n-type semiconductor is formed when dopant atom is:

(1) Monovalent
(2) Bivalent
(3) Trivalent
(4) Pentavalent

Ans: (4)