NEB Class 12 Physics Question Paper 2082 (1021'H') with Answers | PDF
National Examinations Board · Class 11–12
NEB 2082 Class 12 Physics question paper
NEB 2082 Class 12 Physics (1021'H') has 22 questions worth 75 marks, with 3 hours to answer them. It has 11 of 1 mark, 8 of 5 marks and 3 of 8 marks.
The Class 12 examination is conducted by the National Examinations Board (NEB), Nepal. This paper was typed up from the original and checked by the GyanMul team.
Every question is given in Nepali and English, as the paper prints it.
The account is free. Timer, marking, worked answers and help from Gurubaa, in one place.
Questions
Answers are shown for the 11 one-mark questions. They are GyanMul's model answers: the NEB does not publish an answer key, so these are not the board's answers.
Question 11 mark
What is the difference between moment of inertia of a rod about an axis passing through its one end and through its centre perpendicular to its length ?
(A)ML2/3(B)ML2/4(C)ML2/6(D)ML2/12
Questions learners ask
How many questions and marks are in the NEB 2082 Class 12 Physics (1021'H') paper?
22 questions worth 75 marks. There are 11 of 1 mark, 8 of 5 marks and 3 of 8 marks.
How much time is given for this paper?
3 hours (180 minutes).
Is this the real board paper?
Yes. It is the NEB 2082 paper, code 1021'H', typed up from the original and checked by the GyanMul team.
Are the answers included?
Answers to the 11 one-mark questions are on this page (GyanMul's model answers; the NEB does not publish an answer key). Worked answers and the marking for every other question are in GyanMul Prep, free with an account.
Can I download this paper as a PDF?
Yes. Press "Print / Save as PDF" at the top of the page and choose "Save as PDF" in your browser's print window.
कुनै छडको एउटा छेउबाट गुज्रने अक्ष र त्यसको केन्द्रबाट लम्ब रूपमा गुज्रने अक्षका सापेक्ष जडत्व आघूर्णबिचको अन्तर कति हुन्छ ?
(A)ML2/3(B)ML2/4(C)ML2/6(D)ML2/12
Answer:ML2/4
Question 21 mark
For an oscillating object, the displacement versus time curve shown in figure. What is the velocity of the object in the mean position ?
(A)0.2πm/s(B)0.4πm/s(C)2πm/s(D)4πm/s
दोलन गरिरहेको कुनै वस्तुको विस्थापन-समय वक्र चित्रमा देखाइएको छ । मध्य स्थितिमा वस्तुको वेग कति हुन्छ ?
(A)0.2πm/s(B)0.4πm/s(C)2πm/s(D)4πm/s
Answer:0.2πm/s
Question 31 mark
Two spherical rain drops of equal size are falling vertically downward with terminal` velocity of 0.15m/s. What would be the terminal velocity if these drops were combined to form a larger drop ?
(A) 0.15 m/s (B) 0.24 m/s (C) 0.31 m/s (D) 0.48 m/s
समान आकारका दुई गोलाकार वर्षाका थोपा 0.15 m/s को सीमान्त वेगले ठाडो तल खसिरहेका छन् । ती थोपा मिलेर एउटा ठुलो थोपा बने भने सीमान्त वेग कति हुन्छ ?
(A) 0.15 m/s (B) 0.24 m/s (C) 0.31 m/s (D) 0.48 m/s
Answer:0.24 m/s
Question 41 mark
What happens in an adiabatic process ?
(A) Volume remains constant (B) Pressure remains constant (C) Temperature remains constant (D) The system is insulated from the surroundings
रुद्धोष्म प्रक्रियामा के हुन्छ ?
(A) Volume remains constant (B) Pressure remains constant (C) Temperature remains constant (D) The system is insulated from the surroundings
Answer:The system is insulated from the surroundings
Question 51 mark
The efficiency of Carnot engine operating between steam point and ice point is
(A) 26.8% (B) 50% (C) 73.2% (D) 100%
भाप बिन्दु र हिम बिन्दुबिच चल्ने कार्नो इन्जिनको दक्षता कति हुन्छ ?
(A) 26.8% (B) 50% (C) 73.2% (D) 100%
Answer:26.8%
Question 61 mark
Which of the following is an example of transverse wave ?
(A) Sound wave in air (B) Waves inside the water (C) Wave produced in the stem of vibrating tuning fork (D) Wave produced in the stretched string
तलका मध्ये कुन अनुप्रस्थ तरङ्गको उदाहरण हो ?
(A) Sound wave in air (B) Waves inside the water (C) Wave produced in the stem of vibrating tuning fork (D) Wave produced in the stretched string
Answer:Wave produced in the stretched string
Question 71 mark
Which one of the following phenomena is not explained by Huygen's construction of wave front ?
(A) refraction (B) reflection (C) polarization (D) diffraction
हाइगेन्सको तरङ्गाग्र रचनाले तलका मध्ये कुन घटना व्याख्या गर्न सक्दैन ?
(A) refraction (B) reflection (C) polarization (D) diffraction
Answer:polarization
Question 81 mark
The magnetic field intensity at the center of a circular coil of radius R and carrying current I is
(A)μ0I/R(B)μ0I/2R(C)μ0I/2πR(D)2μ0I/R
R त्रिज्या भएको र I विद्युत् धारा बगिरहेको वृत्ताकार कुण्डलीको केन्द्रमा चुम्बकीय क्षेत्रको तीव्रता कति हुन्छ ?
(A)μ0I/R(B)μ0I/2R(C)μ0I/2πR(D)2μ0I/R
Answer:μ0I/2R
Question 91 mark
If χ is the magnetic susceptibility of a material then its relative permeability (μr) is
(A)χ+1(B)χ−1(C)1/χ(D)1+χ2
कुनै पदार्थको चुम्बकीय ग्रहणशीलता χ भए त्यसको आपेक्षिक चुम्बकशीलता (μr) कति हुन्छ ?
(A)χ+1(B)χ−1(C)1/χ(D)1+χ2
Answer:χ+1
Question 101 mark
A square coil of area 10−2m2 is placed perpendicular to a uniform magnetic field of intensity 103T. What is the magnetic flux through the coil ?
(A) 100 Weber (B) 10 Weber (C)10−3 Weber (D)10−5 Weber
10−2m2 क्षेत्रफलको वर्गाकार कुण्डली 103T तीव्रताको एकसमान चुम्बकीय क्षेत्रको लम्ब राखिएको छ । कुण्डलीबाट गुज्रने चुम्बकीय फ्लक्स कति हुन्छ ?
(A) 100 Weber (B) 10 Weber (C)10−3
Answer:10 Weber
Question 111 mark
What is the point where the Seismic waves start called ?
(A) Epicenter (B) Metacenter (C) Hypocenter (D) Seismic center
भूकम्पीय तरङ्गहरू सुरु हुने बिन्दुलाई के भनिन्छ ?
(A) Epicenter (B) Metacenter (C) Hypocenter (D) Seismic center
Answer:Hypocenter
Question 125 marks
(ग) पृथ्वीको सतहमा सरल लोलकको आवर्त काल T छ । चन्द्रमाको सतहमा त्यो कति हुन्छ ? [1]
a) A ballet dancer sometimes stretches and sometimes folds her arms during her performance, why ? Justify. [2]
b) Establish a relation between torque and moment of inertia for a rigid body. [2]
c) Why do we prefer a wrench of longer arm over a wrench of shorter arm ? [1]
OR
a) Show that the total energy of the particles executing SHM is constant. [3]
b) Draw a graph showing the variation of potential energy of particle in SHM with displacement. [1]
c) The time period of simple pendulum on the surface of earth is T. What will be its time period on the Moon's surface ? [1]
(क) नर्तकीले नृत्यका क्रममा कहिले पाखुरा फैलाउँछिन् र कहिले खुम्च्याउँछिन्, किन ? पुष्टि गर्नुहोस् । [2]
(ख) दृढ पिण्डका लागि बलआघूर्ण र जडत्व आघूर्णबिचको सम्बन्ध स्थापित गर्नुहोस् । [2]
(ग) छोटो हाते रिन्चभन्दा लामो हाते रिन्च किन रोजिन्छ ? [1]
अथवा (OR)
(क) सरल आवर्त गति गरिरहेको कणको कुल ऊर्जा स्थिर हुन्छ भनी देखाउनुहोस् । [3]
(ख) सरल आवर्त गतिमा कणको स्थितिज ऊर्जा र विस्थापनबिचको सम्बन्ध ग्राफमा देखाउनुहोस् । [1]
(ग) पृथ्वीको सतहमा सरल लोलकको आवर्त काल T छ । चन्द्रमाको सतहमा त्यो कति हुन्छ ? [1]
अथवा
a) Define laminar flow and turbulent flow of liquid. [2]
b) Water flows steadily through a horizontal pipe of non-uniform cross section. If the pressure of water is 4×104Nm−2 at a point where the velocity of flow is 2 m/s and cross section is 200cm2. Calculate the pressure at a point where cross section reduces to 50cm2. (density of water =1000kg/m3)[3]
(क) तरलको धारारेखीय र विक्षुब्ध प्रवाह परिभाषित गर्नुहोस् । [2]
(ख) असमान अनुप्रस्थ काट भएको तेर्सो पाइपबाट पानी समान दरले बगिरहेको छ । जुन बिन्दुमा प्रवाहको वेग 2 m/s र अनुप्रस्थ काट 200cm2 छ, त्यहाँ पानीको दाब 4×104Nm−2 छ । अनुप्रस्थ काट घटेर 50cm2
a) A Carnot's engine has 25% efficiency with a sink at 90C. By how many degrees should the temperature of the source be increased in order to raise the efficiency to 50% ? [3]
b) State first law of thermodynamics. Does it follow the principle of conservation of energy ? Explain. [2]
(क) 90C को सिंक भएको कार्नो इन्जिनको दक्षता 25 % छ । दक्षता 50 % पुर्याउन स्रोतको तापक्रम कति डिग्रीले बढाउनुपर्छ ? [3]
(ख) ऊष्मागतिकीको पहिलो नियम लेख्नुहोस् । के त्यसले ऊर्जा संरक्षणको सिद्धान्त पछ्याउँछ ? व्याख्या गर्नुहोस् । [2]
a) Discuss the effect of temperature and pressure on velocity of sound in a gas. [2]
b) A train is approaching a cliff at 10m/s. The driver sounds a whistle of frequency 600Hz. What will be the frequency of echo as heard by the driver ? (Velocity of sound in air =340ms−1)[3]
(क) ग्याँसमा ध्वनिको वेगमा तापक्रम र दाबको प्रभावबारे चर्चा गर्नुहोस् । [2]
(ख) एउटा रेल 10 m/s को वेगले भीरतर्फ आउँदै छ । चालकले 600 Hz आवृत्तिको हुइसल बजाउँछ । चालकले सुन्ने प्रतिध्वनिको आवृत्ति कति हुन्छ ? (हावामा ध्वनिको वेग =340ms−1)[3]
a) State the two Kirchhoff's laws of electrical circuit. [2]
b) Obtain an expression for the balanced condition of Wheatstone bridge using Kirchhoff's laws. [3]
(क) विद्युत् परिपथका किर्चफका दुई नियम लेख्नुहोस् । [2]
(ख) किर्चफका नियम प्रयोग गरी ह्विटस्टोन सेतुको सन्तुलित अवस्थाको व्यञ्जक निकाल्नुहोस् । [3]
a) State Lenz's law. [1]
b) Plot a graph to show the variation of induced emf in a coil rotating in a uniform magnetic field with time. [1]
c) Derive an expression for the energy stored in an inductor. [3]
(क) लेन्जको नियम लेख्नुहोस् । [1]
(ख) एकसमान चुम्बकीय क्षेत्रमा घुमिरहेको कुण्डलीमा उत्पन्न हुने प्रेरित विद्युत् वाहक बल र समयबिचको सम्बन्ध ग्राफमा देखाउनुहोस् । [1]
(ग) प्रेरकमा सञ्चित ऊर्जाको व्यञ्जक व्युत्पन्न गर्नुहोस् । [3]
(क) क्षय स्थिरांक र अर्ध आयु परिभाषित गर्नुहोस् । [2]
(ख) रेडियोधर्मी प्रक्रियाका लागि N=N0e−λt समीकरण व्युत्पन्न गर्नुहोस्, जहाँ सङ्केतहरूको सामान्य अर्थ छ । [3]
a) An oil drop of mass 3×10−11g and of radius 2×10−4cm carries 10 excess electrons. What is its terminal velocity when
i) falling in a region in which there is no electric field ? [1]
ii) falling in an electric field of 3×105Vm−1 directed downward ? (Viscosity of air =1.8×10−5NSm−2)[1]
b) In Thomson's method for determining specific charge of an electron, why is the electric field kept perpendicular to magnetic field ? Justify. [2]
c) What is the use of X-rays in Millikan's oil drop experiment ? [1]
OR
a) Define decay constant and half life. [2]
b) Derive the equation : N=N0e−λt for radioactive process where symbols have there usual meanings. [3]
(क) 3×10−11g द्रव्यमान र 2×10−4cm त्रिज्या भएको तेलको थोपाले 10 अतिरिक्त इलेक्ट्रोन बोकेको छ । यसको सीमान्त वेग कति हुन्छ —
(i) विद्युतीय क्षेत्र नभएको ठाउँमा खस्दा ? [1]
(ii) तल दिशामा 3×105Vm−1
(ग) ब्रुस्टरको नियम लेखी प्रमाणित गर्नुहोस् । [2]
a) What are stationary waves ? Prove that the distance between two consecutive nodes in it is equal to half of the wavelength. [3]
b) Guitar string of length 1.5m is made of steel of density 7800kg/m3 and Young's modulus 2×1011N/m2. It produces an elastic strain of 1% in the string. Calculate [3]
i) stress developed in the string.
ii) frequency of second mode of vibration.
c) The given figure shows standing wave formed in an open organ pipe.
i) Which mode of vibration is shown ? [1]
ii) Obtain the frequency of vibration for this mode. [1]
OR
a) Prove that bright and dark fringes are equally spaced in Young's double slit experiment. [3]
b) A parallel beam of monochromatic light is incident on diffraction grating having 500 lines/mm to get second order maxima at 300. Calculate the wavelength of light used. [3]
c) State and prove Brewster's law. [2]
(क) अप्रगामी तरङ्ग भनेको के हो ? त्यसमा दुई क्रमिक निस्पन्दबिचको दूरी तरङ्गदैर्घ्यको आधा हुन्छ भनी प्रमाणित गर्नुहोस् । [3]
(ख) 1.5 m लामो गिटारको तार 7800kg/m3 घनत्व र 2×1011N/m2
a) The figure below shows a series LCR circuit.
If the frequency of an ac source is 500/πHz then,
i) Calculate the phase angle between current and voltage. [2]
ii) Which one leads in phase, current or voltage ? Justify. [1]
b) What is meant by impedance of an ac circuit ? [1]
c) Two parallel wire P and Q carrying currents I1 and I2 are placed in the air at a distance r apart as shown in figure.
i) Obtain an expression for the magnitude of force per unit length between them. [2]
ii) What is the nature of force in this case ? [1]
iii) What will be the force per unit length between two wires if distance between wires is halved, keeping all other quantities constant ? [1]
OR
a) Explain the variation of thermoelectric emf with the temperature of the hot junction of a thermocouple. [3]
b) A potentiometer circuit is shown in figure. If the total length of potentiometer wire is 4m and has resistance 10Ω and the balance point is obtained at a length of 240cm, calculate the value of unknown emf E. [3]
c) Use ampere's circuital law to find the magnetic field due to a straight current carrying conductor. [2]
(क) तलको चित्रले श्रेणीबद्ध LCR परिपथ देखाउँछ । प्रत्यावर्ती स्रोतको आवृत्ति 500/πHz छ भने —
(i) धारा र भोल्टेजबिचको कला कोण गणना गर्नुहोस् । [2]
(ii) कलामा कुन अगाडि हुन्छ, धारा कि भोल्टेज ? पुष्टि गर्नुहोस् । [1]
(ख) प्रत्यावर्ती परिपथको प्रतिबाधा भनेको के हो ? [1]
(ग) I1 र I2
a) Define threshold wavelength. [1]
b) A metal has a work function of 2eV. Calculate the maximum speed of the emitted photoelectrons when it is illuminated by radiation of wavelength 150nm. What is the least frequency of the radiation for which electrons are emitted ? (Given : Planck's constant h=6.62×10−34Js,m=9.1×10−31Kg,e=1.6×10−19C)[3]
c) State Heisenberg's Uncertainty principle. [1]
d) Obtain an expression for velocity of an electron in nth orbit of hydrogen atom. [3]
(क) देहली तरङ्गदैर्घ्य परिभाषित गर्नुहोस् । [1]
(ख) कुनै धातुको कार्य फलन 2 eV छ । 150 nm तरङ्गदैर्घ्यको विकिरणले प्रकाशित गर्दा उत्सर्जित प्रकाश-इलेक्ट्रोनको अधिकतम गति गणना गर्नुहोस् । इलेक्ट्रोन उत्सर्जन हुने न्यूनतम आवृत्ति कति हो ? (दिइएको : प्लाङ्क स्थिरांक h=6.62×10−34Js,m=9.1×10−31kg,e=1.6×10−19C)[3]
को विद्युतीय क्षेत्रमा खस्दा ? [1]
(हावाको श्यानता
=1.8×10−5NSm−2)
(ख) इलेक्ट्रोनको विशिष्ट आवेश पत्ता लगाउने थोम्सनको विधिमा विद्युतीय क्षेत्र चुम्बकीय क्षेत्रको लम्ब किन राखिन्छ ? पुष्टि गर्नुहोस् । [2]
(ग) मिलिकनको तेल थोपा प्रयोगमा X-किरणको के उपयोग छ ? [1]
अथवा (OR)
(क) क्षय स्थिरांक र अर्ध आयु परिभाषित गर्नुहोस् । [2]
(ख) रेडियोधर्मी प्रक्रियाका लागि
N=N0e−λt
समीकरण व्युत्पन्न गर्नुहोस्, जहाँ सङ्केतहरूको सामान्य अर्थ छ । [3]
अथवा
यङ गुणांक भएको स्टिलले बनेको छ । त्यसमा 1 % प्रत्यास्थ विकृति उत्पन्न हुन्छ । गणना गर्नुहोस् — [3]
(i) तारमा उत्पन्न प्रतिबल
(ii) कम्पनको दोस्रो विधाको आवृत्ति
(ग) दिइएको चित्रले खुला अर्गन पाइपमा बनेको अप्रगामी तरङ्ग देखाउँछ ।
(i) कुन कम्पन विधा देखाइएको छ ? [1]
(ii) यस विधाको कम्पन आवृत्ति निकाल्नुहोस् । [1]
अथवा (OR)
(क) यङको द्वि-झिर्को प्रयोगमा उज्याला र अँध्याका पट्टीहरू समान अन्तरमा हुन्छन् भनी प्रमाणित गर्नुहोस् । [3]
(ख) प्रति mm 500 रेखा भएको विवर्तन जालीमा एकवर्णी प्रकाशको समानान्तर पुञ्ज पारेर
300
मा दोस्रो कोटिको अधिकतम पाइन्छ । प्रयोग गरिएको प्रकाशको तरङ्गदैर्घ्य गणना गर्नुहोस् । [3]
(ग) ब्रुस्टरको नियम लेखी प्रमाणित गर्नुहोस् । [2]
अथवा
धारा बगिरहेका दुई समानान्तर तार P र Q हावामा r दूरीमा चित्रमा देखाएझैँ राखिएका छन् ।
(i) तिनीबिच प्रति एकाइ लम्बाइमा लाग्ने बलको परिमाणको व्यञ्जक निकाल्नुहोस् । [2]
(ii) यस अवस्थामा बलको प्रकृति कस्तो हुन्छ ? [1]
(iii) अरू सबै राशि उही राखी तारबिचको दूरी आधा गरे प्रति एकाइ लम्बाइमा बल कति हुन्छ ? [1]
अथवा (OR)
(क) तापयुग्मको तातो सन्धिको तापक्रमसँगै तापविद्युतीय वि.वा.बल कसरी बदलिन्छ, व्याख्या गर्नुहोस् । [3]
(ख) चित्रमा पोटेन्सियोमिटर परिपथ देखाइएको छ । पोटेन्सियोमिटर तारको कुल लम्बाइ 4 m र प्रतिरोध
10Ω
छ, र सन्तुलन बिन्दु 240 cm मा पाइन्छ भने अज्ञात वि.वा.बल E को मान गणना गर्नुहोस् । [3]
(ग) एम्पियरको परिपथीय नियम प्रयोग गरी सिधा धारावाही चालकले उत्पन्न गर्ने चुम्बकीय क्षेत्र निकाल्नुहोस् । [2]
अथवा
