Ampere's Law & applications

 

Argentina 3-3 France (4-2 on penalties)

 

Lionel Messi leads Argentina to World Cup glory despite Kylian Mbappe hat-trick. Messi has led Argentina to World Cup glory after the most thrilling final in the 92-year history of the tournament.

Argentina took the lead through Messi and Angel Di Maria, only for Kylian Mbappe to score a late brace. Messi restored Argentina’s lead in extra time, but Mbappe again hit back for France, completing his hat-trick and taking the game to a penalty shootout.

Argentina won the shootout 4-2, to claim the World Cup and victory in one of the sport’s all-time great games.

World cup 2022 final Argentina vs France tonight

 Argentina are anticipating add another star to their shirt as they haven't had the option to win the world cup beginning around 1986. France, additionally with two cups added to their repertoire, will attempt to turn into the primary group since Brazil in 1962 to win the prize for two continuous years.

Outline

After different legends of the game like Criistiano Ronaldo, Luis Suarez, Robert Lewandowski, Luka Modric and Manuel Neuer had their last world cup appearances at Qatar 2022, it will be Lionel Messi who'll play his last global game for Argentina this evening. This match will likewise offer a chance to the upcoming legends like Kylian Mbappe and Julian Alvarez to win it for their group.

Argentina

This will be Argentina's fifth match (out of complete seven matches) at the Lusail Arena in this competition. It is a similar setting where the Albicelestes lost to Saudi Arabia in their initial match. It is likewise a similar setting where Lionel Scaloni's young men have stayed successful from that point onward. Messi has verified practically each of the things on his football list of must-dos, except for the greatest one of all — the world cup.

Argentina, in the wake of winning five sequential matches at Qatar 2022, will get an opportunity to say the seven-time Ballon d'Or victor a suitable goodbye. Notwithstanding, Messi knows that the greatest game on the planet can't be vanquished by just a single individual's endeavors. This evening, the whole group should convey. The main other group to win the world cup last subsequent to losing their initial match was Spain in 2010.

France

Les Bleus will play at the Lusail Arena without precedent for this competition and attempt to make this critical. They will be the first reigning champs in quite a while to partake in a world cup last, on account of their 2-0 win against Morocco. The most outstanding aspect for France is that their headliners, Mbappe and Olivier Giroud, have been in colossal structure - both holding an opportunity to win the Brilliant Boot by scoring in the last.

Giroud's presentation has been especially exceptional in light of the fact that France relied a ton upon the one he supplanted not long before the world cup - ruling Ballon d'Or victor Karim Benzema. France kept a spotless sheet in the semi-last against Morocco in spite of the African group giving them a panic with their consecutive assaults. Presently, as Didier Deschamps' young men will search for greatness, preventing Argentina from scoring will give them a fantastic benefit.

Date, Time and Setting

The Argentina versus France match will be played on December 18 at 08:45 PM (Nepal time) in the Lusail Arena, Lusail.

PHYSICS XII 2079 question paper( NEB)

 

 

    Physics - Grade XII

Examination - 2079 (2022)

 

Time - 3 hrs

Full Marks - 75

Pass Marks - 27

Candidates are required to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.

 

Group 'A'                    11 x 1 = 11

Rewrite the correct options of each questions in your answer sheet.

1. In rotational motion, the physical quantity that imparts angular acceleration is,

 (A) Force

(B)Torque

(C) Moment of inertia

(D) Angular momentum

2.

 

3. A liquid does not wet the surface of a solid if the angle of contact is,

(A) 90°

(B) less than 90°

(C) Greater than 90°

(D) 0°

 

4. Identify the wrong statement

(A) for isothermal process, ∆T=0

(B) for isochoric process, ∆V= 0

(C) for isobaric process, ∆P=0

(P) for cyclic process, ∆W: 0

 

5.The maximum efficiency an engine operating between 30°C and 300°C is.

(A) 4.71%

(B) 47%

(C) 90%

(D) 9%

 

6.In which frequency range the infrasonic wave lies?

(A) (10-20)Hz

(B) (30-40)Hz

(C) (20-30)Hz

(D) (50-60)Hz

 

7. In Fraunhofer diffraction, the incident wave front should be,

(A) elliptical

(B) plane

(C) spherical

(D) cylindrical

 

8. If specific resistance of a potentiometer wire is 10^-7Ωm, current flowing

through it is 0.1A and cross sectional area of wire is 10^-6 m², then potential

gradient will be.

(A) 10^-2V/m

(B) 10^-4 V/m

(C) 10^-6 V/m

(D) 10^-8V/m

 

9. A coil having N-number of turns and cross-section area A carries a current I. The quantity NIA is.

(A) magnetic flux

(B) magnetic field

(C) magnetic susceptibility

(D) magnetic moment

 

10. At resonance, in series LCR circuit, which relation does not hold good,

(A) ω=1/√Lc

(B) Lω=1/Cω

(C) Cω=1/ Lω

(D) ω=1/Lc

 

11. Which of the following one is correct?

(A) E²=P²C

(B)E²=P²C²

(C) E²=PC²

(D) E²=P²/C²

 

Group 'B' 

8x5=40

12)The angular speed is inversely proportional  to the moment of inertia, that is given by the principal of conservation of energy.  

a) In a flywheel most of the mass is concentrated at the rim? Explain why?   1

b) The angular velocity of the earth around the sun increases, when it comes closer to the sun. Why?    2

c) If the earth were to shrink suddenly, what would happen to the length of the day?   2

 

13) Simple harmonic motion is defined from periodic functions like sine or cosine functions.

a) State the basic equation of motion for a body executing simple harmonic motion.   1

b) Find expression for velocity and acceleration of a particle describing SHM.    2

c) The tip of turning fork goes through 550 complete vibrations in 1 sec. Find the angular frequency and time period of the motion.    1+1=2

OR

a) Define surface tension    1

b) State Bernoulli's theorem.    1

c) Castor oil at 20°C has a coefficient of viscosity 2.42 Nsm² and density 940 kgm³.Calculate the terminal velocity of a steel ball of radius 2mm falling under the gravity in the oil, taking the density of steel as 7800kg/m³(g=10m/s²)      3

14. Adiabatic process   1

a) Define a diabetic process in thermodynamics.  3

b) Derive expression for work done during adiabatic process.   1

c) Write the mathematical expression of entropy.    1

15. a) Define an organ pipe.    1

b) Describe the various modes of vibration of the air column in a closed organ pipe.   3

c) What is end correction?   1

OR

a) State Doppler's effect.    1

b) Derive the apparent frequency of sound when an observer moves towards a stationary source.   2

c)A stationary motion detector sends sound waves of 150 KHz towards a truck approaching at a speed of 120km/hr. What is the frequency of wave reflected back to detector? (Velocity of sound in air =340m/s)    2

16. a)Differentiate See beak's effect and Peltier's effect.   2

b)Explain the variation of thermo-emf with temperature.   3

17) When  a charge particle moves in a uniform magnetic field, it experiences a force called the Lorentz force?    1

a) What is the vector representation of Lorentz force?   1

b) State Fleming left hand rule.   1

c) A horizontal straight wire 5 cm long weighing 1.2gm¹ is placed perpendicular to a uniform horizontal magnetic field of flux density 0.6T. If the resistance of the wire is 3.82 Ωm¹, calculate the p.d. that has to be applied between the ends of the wire to make it just self-supporting.    3

18. Electron is deviated in electric and magnetic fields.

a) What path does the electron follow in electric field when the electron is projected normally in the field ?  1

b) An electron passes through a space without deviation. Does it mean, there is no fields?  2

c) Is there any condition that an electron does not experience any force inside the magnetic field?   2

19. What is rectification?  1

b) Explain rectifier circuit operation with two diodes. 3

c) What happens when one of the diode becomes functionless?  1

Group 'C'    8x3=24

20. a) Write sustainable conditions for interference?  2

b)"The bright and dark fringes are equally spaced." Justify this statement from Young's double slit experiment.  3

c) In a Young's slits experiment the separation of first to fifth fringes is 2.5 mm when the wave length used is 620 cm. The distance from the slits to the screen is 80 cm. Calculate the separation of two slits.   3

21. Kirchhoff's laws in electricity are very useful in solving the complicated circuit connections.

a) What is the significance of first law ?   1

b) State and explain second law with circuit diagram.  2

c) Apply these laws calculate unknown value of resistance.  3

d) What is meter bridge ? Write name of material used to construct meter bridge.    1+1=2

OR

a) Derive the expression for impedance in L-C-R circuit. 3

b) Find the condition of resonance L-C-R circuit.  2

c) A circuit consists of a capacitor of 2µF and a resistor of 1000Ω. An alternating emf of 12V (rms) and frequency 50 Hz is applied. Find the current flowing, the voltage across capacitor and the phase angle between the applied emf and current.   3

22.) State Bohr's postulate of atomic model.  2

b) Derive an expression for radius of n^th orbit in H-atom.   3

c) Calculate de Brogle wavelength of electron when it is accelerated by 500 volt. ( mass of electron 9.1x10^-31 kg, Planck's constant 6.62x10^-34Js, charge of electron 1.6x10^-19C)    3

OR

Radio activity is the spontaneously occurring phenomenon in nature.

a) What is radio activity?  1

b) Obtain N= N₀e^-λ^t in radio active decay law.  3

c) Describe the significance of decay curve showing the longest life time

of radio-isotopes.  1

d)The half-life of radium is 1620 years. After how many years 25% of a radium block remains undecayed ?  3

 

Physics XII 2078 Question paper( NEB )

 

    Physics - Grade XII

Examination - 2078 (2021)

 

 

Time - 3 hrs

Full Marks - 75

Pass Marks - 27

Candidates are required to give their answers in their own words as far as practicable. The figures in the margin indicate full marks.

 

Group A: Multiple Choice Questions (11 x 1 =11)

1. Which of the following is a correct formula for calculating the radius of gyration of a rotating object?
A) k²= I/m
B) k= I/m
C) k= m/I
D) k = (I/m)²

2. A horizontal stream of air is blown under one of the pans of a beam balance as shown in the figure. What will be the effect of this on the pan?

A) goes up
B) goes down
C) remains unaffected
D) rotates

3. What will be the height of a capillary on the surface of the Moon if it is h on Earth?
A) h
B) h/6
C) 6h
D) zero

4. What is the coefficient of performance of an ideal refrigerator working between ice point and room temperature (27°C)?
A) 0
B) 0.1
C) 1
D) 10

5. A thermodynamic system is taken from A to B via C and then returned to A via D as shown in the P-V diagram. The area of which segment of the graph represents the total work done by the system?

A) P₁ACBP₂P₁
B) ACBB’A’A
C) ACBDA
D) ADBB’A’A

6. Which one of the following directly affects the quality of sound?
A) Shape of the source
B) frequency
C) intensity
D) wave form

7. A diffraction pattern is obtained using a beam of red light. What will be the effect on the diffraction pattern if the red light is replaced with white light?
A) All bright fringes become white.
B) All bright fringes, except the central one, become white.
C) All bright fringes become colourful.
D) All bright fringes, except the central one, become colourful.

8. In which one of the following diagrams the currents are related by the equation I₁ – I₂ = I₃ – I₄?

9. A coil having N turns and cross-section area A carries current I. Which physical quantity does the product NIA represent?
A) magnetic flux of the coil
B) magnetic flux density of the coil
C) magnetic moment of the coil
D) magnetic susceptibility of the coil

10. What happens to the neutral temperature if the cold junction of a thermocouple is decreased?
A) increases
B) decreases
C) remains the same
D) approaches inversion temperature

11. What is the point where the seismic waves start called?
A) epicentre
B) hypocentre
C) metacentre
D) seismic centre

GROUP ‘B’ Short Answer Questions (8 x 5 = 40)

1. (i) Define surface tension. [1]
   (ii) Establish a relation between surface tension and surface energy of a liquid. [2]
   (iii) Two spherical rain drops of equal size are falling vertically through air with a certain terminal velocity. If these two drops were to coalesce to form a single drop and fall with a new terminal velocity, explain how the terminal velocity of the new drop compares to the original terminal velocity. [2]

2. Angular speed of a rotating body is inversely proportional to its moment of inertia.
   (i) Define moment of inertia. [1]
   (ii) Explain why angular velocity of the Earth increases when it comes closer to the Sun in its orbit. [2]
   (iii) If the Earth were to shrink suddenly, what would happened to the length of the day? Give reason. [2]

OR

(i) State Bernoulli principle. [1]
(ii) Derive Bernoulli’s equation. [2]
(iii) You can squirt water from a garden hose a considerably greater distance by partially covering the opening with your thumb. Explain how this works. [2]

3. (i) Define ‘harmonics’ in music. [1]
   (ii) Calculate the frequency of a monotonous sound produced by a 30 cm long flute open at both ends and being played in the first harmonic. [Velocity of sound in air= 330 ms-1] [2]
   (iii) The flute mentioned in question (ii) was being played by a passenger on a stationary bus. The bus then moves uniformly. Explain what change in the pitch of the flute sound, if any, a person sitting on a bench at the bus park will feel when the bus starts moving. [2]

4. 
   
   (i) State the second law of thermodynamics. [1]
   (ii) A refrigerator transfers heat from a cold body to hot body. Does this not violate the second law of thermodynamics? Give reason. [2]
   (iii) In the given figure, a heat engine absorbs Q₁ amount of heat from a source at temperature T₁ and rejects Q₂ amount of heat to a sink at temperature T₂ doing some external work W.
   

 

(a) Obtain an expression for the efficiency of this heat engine. [1]
(b) Under what condition does the efficiency of such engine become zero percentage, if at all? [1]

5. A student wants to measure the magnetic flux density between the poles of two weak bar magnets mounted on a steel yoke as shown in the figure. The magnitude of the flux density is between 0.02T and 0.04T.
   
   
   
6. (i) Define Magnetic flux density. [1]
   (ii) One way of measuring the magnetic flux density could be the use of a Hall probe. Suggest one reason why Hall probe is not a suitable instrument to measure the magnetic flux density for the arrangement shown in the below figure. [1]
   
   (iii) Another method of measuring the magnetic flux density for the arrangement shown in the above figure is to insert a current-carrying wire between the poles of the magnet. Explain how the magnetic flux density can be determined using this method. You are
   allowed to use any additional apparatus. [3]

 

6. 
   (a) Law of electromagnetic induction can be expressed mathematically as ε = -N(dϕ/dt).
   (b) (i) State what the symbols ε and dϕ/dt represents in the equation. [2]
   (ii) Explain the significance of the negative sign. [1]
   (ii) Two identical copper balls are dropped from the same height as shown in the figure. Ball P passes through a region of uniform horizontal magnetic filed of flux density B.
   Explain why ball P takes longer than ball Q to reach the ground. [2]

 

7. Ultraviolet radiation of frequency 1.5 × 10¹⁵Hz is incident on the surface of an aluminium plate whose work function is 6.6×10^-19J.
   (i) Show that the maximum speed of the electrons emitted from the surface of the aluminium is 8.6 × 10⁵ms^–1. [3]
   (ii) State and explain what change, if any, occurs to the maximum speed of the emitted electrons when the intensity of the ultraviolet radiation is increased. [2]

8. (i) State Bohr‟s postulates of atomic model. [3]
   (ii) The figure shows Lyman series of energy transmission in hydrogen atom. Calculate the frequency of a photon emitted by an electron jumping from the second excited state to the ground level. [2]

OR

(i) Sketch the symbol of a p-n junction diode and indicate the polarity of its ends. [1]
(ii) Copy the outline of a diode bridge rectifier and complete it by adding diodes in the gaps. [2]

 

(iii) Explain what will happen if one of the four diodes is damaged so that it stops conducting totally in any direction. Sketch a graph to show how the pd across the Load R_L would vary with time in this situation. [2]

Section C: Long Answer Questions. (3 × 8 = 24)

9. Earthquake sets rocks and buildings in motion. When a rock is subjected to compression, a restoring force develops inside it. This restoring force is given by an equation F= -Ax where x is displacement and A is a constant.
   (i) Prove that this force will make the rock vibrate with simple harmonic motion. [2]
   (ii) Show that the speed of an object undergoing simple harmonic motion is given by the expression v = ±ω√(A²-x²) where the symbols carry standard meanings. [2]
   (ii) Calculate the maximum speed of a building shaken by S-waves of 21Hz and amplitude 0.05m. [2]
   (iv) Explain why tall buildings are more susceptible to damage by S-waves which generally have low frequency. [2]

10. The figure below shows the variation of emf and current with time in a typical LRC circuit.
    (i) Explain whether the phase constant is postive or negative. [2]
    (ii) Sketch a phasor diagram for the given case. [2]
    (iii) Is the circuit more inductive or capacitive? Explain. [2]
    (iv) To increse the rate at which energy is transferred to the resistive load, should the inductance be increased or decreased? Justify your answer. [2]

OR

A student sets up a circuit as shown in the figure given below to measure the emf of a test cell.

1. Explain why he is unable to find a balance point and state the change he must make in order to achieve the balance.[2]
2. State how he would recognize the balance point. [1]
3. He obtained the balance point for distance 37.5cm using standard cell of emf 1.50V. And for the test cell, the balance distance AB was 25.0 cm. Calculate the emf of the test cell. [3]
4. He could have used an ordinary voltmeter to measure the emf of the test cell directly. The student, however, argues that the above instrument is more precise than an ordinary voltmeter. Justify his logic. [2]

 

11. (a) Explain what is meant by quantization of charge. [2]
    
    (b) In a Millikan‟s oil drop experiment, an oil drop of weight 1.5 x 10^-14N is held stationary between plates 10mm apart by applying a p.d. of 470V between the plates.

(i) State the condition necessary for the drop to remain stationary. Also, sketch the forces acting on the oil drop. [2]
(ii) Calculate the charge on the oil drop. [2]
(iii) Explain what would happen if the above oil drop is suddenly struck by a stray alpha particle. [2]

OR

(a) Derive an expression N= N_oe-λt for a radioactive process where the symbols carry their standard meanings. [3]
(b) A student measured the activity of a sample of radioactive rock. Her results are presented in the graph.

 

(i) Explain why the data are scattered. [1]
(ii) Determine the half-life of this sample. [2]
(iii) How will the shape of this curve will change if she repeats the experiment with a sample with a larger decay constant. Give reason to your answer. [2]