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  • Test paper Class-11 (Physics)

    This is the first test paper provided for the students of class-11th ( Physics) . in the end of the paper answer is given . Students having solved the question paper , may check its answers.

    This question paper is taken by the other books, if students get any errors , then sorry for this.

    Test-1st-11th-Download

    solution-test-1-11thDownload

  • Very important numericals physics( term-2)

    Important numericals physics term-2 (CBSE)

    1. What is apparent position of the object below a rectangular block of glass 6cm thick , if a layer of water 4cm thick is on the top of the glass ? Refractive index of glass and water with respect to air is 3/2 and 4/3 respectively.
    2. A screen is placed 100cm from an object  . The image of the object on the screen is formed by a convex lens at two different locations , separated by distance 20cm . calculate the focal length of the lens used.
    3. You are given three lenses  L1 , L2,L3 each of focal length 10cm . an object is kept at 15cm in front of L1  ,  as shown in fig. the final image is formed at the focus of L3 find the separation between the lenses.
    • 4. A convex lens made up of glass of refractive index 1.5 is  dipped  , in turn ,in (a) a medium of refractive index 1.65 (b)   ) a medium of refractive index 1.33.Will it behave like converging or diverging lens in two cases, explain how focal length changes in two cases .
    • 5.Three rays  red  , green and blue are incident on a right angled prism ABC at face AB the refractive indices of the material  of the prism for red, green ,and blue are 1.39,1.44, and 1.47 respectively . Out of the three which colour of ray emerge out of face AC. Trace the path of the three rays after passing through AB.
    • 6. State the conditions under which total internal reflection occurs . one face of a prism with a refracting angle of 30 , is coated with silver . A ray incident on  another face at an angle of 45 is refracted and reflected from the silver coated face and retrace its path. Find the refractive index of the material of the prism.
    • 7. Find the position of the image formed by the lens combination given in figure   
    • 8. A diverging lens of focal length f cut into two identical parts ,each forming a plano- convex lens what is the focal length of each part. How the focal length of the lens changes if it bisected axially?
    • 9. The image of a needle placed 45cm from a lens is formed on a screen placed 90 cm on the other side of lens. Find displacement of image if object is moved 5cm away from lens.
    • 10. A small bulb is placed at  the bottom of a tank containing water to a depth of 80 cm . what is the area of the surface of water through which light of the bulb can emerge out ?Refractive index of water is 1.33 consider the bulb to be a point source.
    •  11. Yellow light of wavelength λ= 6000 A illuminate a single slit of width 1 x 10-4 m calculate (i) the distance between two dark lines on either side of the central maximum when the diffraction pattern is on screen kept 1.5 m away from the slits , (ii) the angular spread of the first diffraction minima .

       Ans- 1.8 cm , 6x 10-3 rad . 12. Two wavelength of sodium light 590 nm are used in turn , to study the diffraction taking place at the single slit of aperture  2x 10-4 m . The distance between the slits and the screen is 1.5 m . Calculate the separation between the position of first maxima of the diffraction pattern obtained in the two cases .

      Ans-6.75×10-5m . 13. (a) In a single slit diffraction , a slit of width d is illuminated by red light of wavelength 650 nm . For what value of  d will (i) the first minimum fall at an angle of diffraction of 300 , and   (ii) the first maximum fall at an angle of diffraction of 300 ? 

      (b) Why does the intensity of secondary maximum becomes less as compared to the central maximum .

         Ans- 1.3 x10-6 m , 1.95×10 ‑6‑ m 14. A monochromatic light of wavelength 500 nm is incident normally on a single slit of width 0.2 mm to produce a diffraction pattern . Find the angular width of the central maximum obtained on the screen . Also estimate the number of fringes obtained in YDSE with fringe width 0.5 mm , which can be accommodate within the region of total angular spread of the central maximum due to single slit .            Ans- ϴ=0 to 2.5×10-3 ; n=D/2 ;D+1 15.A beam of light consisting of two wavelength 800nm and 600 nm is used to obtain the interference pattern in YDSE on a screen placed 1.4 m away . If the two slits are separated by 0.28mm , calculate the least distance from the central bright maximum where the bright fringes of the two wavelengths coincide . Ans- n=3 ; 1.2 cm . 16. In YDSE using monochromatic light of wavelength λ, the intensity of light at a point on the screen where path difference is λ is K units . Find out the intensity of light of light at a point where path- difference is λ/3 . 17. The ratio of the intensity at minima to the maxima in YDSE is 9:25 , find the ratio of the width of the two slits , also find the ratio of amplitude .   Ans- 16:1 . 18. Two wavelength of sodium light of 590 nm and 596 nm are used in turn to study the diffraction taking place at a single slit of aperture 2×10-6 m . The distance between the slit and the screen is 1.5 m . Calculate separation between the position of first maxima and of the diffraction pattern obtained in the two cases .

     Ans- 6.75 nm .

    19. The electron in a given Bohr orbit has a total energy of -1.5Ev. calculate its(i) kinetic energy(ii)potential energy (iii) wavelength of the radiation emitted , when this electron makes a transition to the ground state.

    20. The energy of an electron in the ground state of hydrogen atom is -13.6 Ev. (i) what does the negative sign signify ? (ii)how much energy is required to take an electron in this atom from the ground state to the first exited state?

    21. The ground state energy of hydrogen atom is  -13.6 eV.  ( I ) What is the potential energy of an electron in the third exited state? (ii) what will be the maximum and minimum wavelength of the emitted  radiation of Lyman series of hydrogen spectrum.

    22. The energy level diagram  of an element is given below . identify using necessary calculations , which transition corresponds to the emission of the spectral line of wavelength 102.7 nm . which transition corresponds to the emission of radiation of maximum wavelength?  

    .

    23.The first line of Lyman series in hydrogen spectrum has a wavelength of 1220 Å. Calculate the wavelength of the second member of the series.

    24. A nucleus at rest splits up into two parts with velocity ratio 2 : 1 calculate the ratio of their radii of the ratio the two nuclear fragments.

    25.The ground state energy of electron in hydrogen atom is – 13.6 eV. Find the kinetic energy and potential energy of the electron in (i) ground state (ii) first excited state.

  • Physics Sample paper class12th(term-2)

    Sample paper -1

                                                            Class 12th

                                                        Physics (Theory)   Term-2

                                    

    M.M: 35                                                                                                             TIME-2Hrs

     Here Physics classes by Nayan jha providing CBSE Term-2 Physics sample paper .

    There are 12 questions in all and all questions are compulsory.

     This question paper consists of three section A,B and C.

    SECTION A has three questions of two marks each , 

    SECFTION- B there are eight questions carrying three marks each and

    SECTION- C is case study based questions of five marks.

    There is no overall choice . However , an internal choice has been provided.

    Uses of calculator is not allowed.

    SECTION-A

    1. Find the ratio of energies of photons produced due to transition of electron of hydrogen atom from its (i) Second permitted energy level to the first level and, (ii) the highest permitted energy level .

    Or,

    The ground state energy of hydrogen atom is -13.6eV. What is the kinetic and potential energy of electron in this orbit.

    2. Draw the circuit diagram showing the biasing of an LED . State the factor which controls (i) Wavelength of light (ii) intensity of light emitted by the diode.

    3. Write the photoelectric equations of Einstein . Write two basic features of photon picture of electromagnetic radiation on which Einstein’s photoelectric equation is based.

    SECTION-B

    4. Draw V-I characteristics of p-n junction diode (i) When diode is reversed bias and (ii) when diode is forward biased . Explain why the current under reverse bias is almost independent of the applied voltage up to the critical voltage?

    5.State the necessary conditions for producing total internal reflection of light. Draw the diagram to show how specially designed prism make use of T.I.R to obtained inverted image of the object by deviating rays (i) through 900 and (ii) Through 1800.

    Or,

    Three rays of light red , green and blue is fall normally on one of the equal side of an isosceles right angled prism . The refractive index of these rays are 1.39,1.44,1.47 respectively . Find which of these rays get internally reflected from diagonal side . Trace the path of rays . Justify your answer with necessary conditions.

    6. Using Bohr postulates for hydrogen atom , show that the total energy of the electron in the stationary states can be expressed as the sum of kinetic energy(K) and potential energy (U)  , where K=-2U. hence , deduce the expression for the total energy in the nth energy level of hydrogen atom .

    Or,

     Draw a labelled diagram of alpha particle scattering experiment. Give Rutherford observations and  discuss the significance of this experiment .

    7. How the size of nuclei is experimentally determined ? write the relation between the radius and mass number of the nucleus . show that the density of the nucleus is independent of its mass number. Two nuclei of mass number in the ratio 27:125. What is the ratio of their nuclear radius and , ratio of their densities.

    Or,

    Draw the binding energy per nucleon curve . using the curve state clearly how the release in energy in the process of nuclear fission and nuclear fusion can be explained.

    8. An electron of mass m  and charge q is accelerated from rest through a potential difference V  , obtain the expression for the de-Broglie  wavelength  associated with it . if electron and proton are moving with the same K.E. , which one of them will have a large De-Broglie wavelength associated with it ? give reason .

    9. I n a single slit diffraction experiment , deduce the conditions for the central maximum and secondary maxima/minima observed in diffraction pattern . Also explain why the secondary maxima go on becoming weaker in intensity as the order increases. Haw does the width of the slit affected the size of the central bright fringe?

    10. Using Young’s double slit experiment obtain the conditions for gating bright and dark fringes  also derive the expression for the fringe width.  Also write the effect on fringe width when(I)Distance between slits increases/decreases (II) Distance between slits and the screen increases/decreases(III) Monochromatic light replaced  by white light,(IV) One of slit is closed and (V) entire experimental apparatus is immersed in a liquid.

    11.  (i) Which segment of electromagnetic waves has highest frequency? How are these waves produced? Give one use of these waves.

    (ii) Which EM waves lie near the high frequency end of visible part of EM spectrum? Give its one use. In what way this component of light has harmful effects on humans?

                Section-C

    12.

     Power of a lens-

    Power (P) of a lens is given as the reciprocal of focal length (P=1/f)where f should be in meter and P is in Diopter . for convex power is positive and concave power is –ve. When two or more lenses are kept in contact then power of the combined lens is given as P= P1 + P2+P3 …….

    (I) A convex and a concave lens is separated by distance d are then put in contact then the focal length of the combination  (a) becomes 0 (b) remain the same (iii) decreases (iv)increases.

    (ii)The two lenses of power +1.5D and +1.0D are placed in contact then the effective power of the combination will be (a)2.5D (b)1.5 D (c) 0.5D (d)3.25D .

    (iii) If the power of the lens is 5D then what is the focal length of the lens?(a)10cm (b) 20cm (c)15cm (d) 5cm

    (iv)Two thin lens of focal length +10cm and -5cm are kept in contact , the power of the combination is ? (a)-10D (b)-20D (c)10D (d)15D .

    (v)A convex lens of focal length 25cm is placed coaxially in contact with a concave lens of focal length 20cm the system will be ; (a) converging in nature (ii) diverging in nature (c) can be converging or diverging (d) None of the above.

    Samle-paper2-22-12thDownload

    samplpaper-3.pdf

  • Test Dual nature, Atoms Nuclei and semiconductor

    Here physics classes by Nayan jha providing the test paper based on the chapter Dual nature, Atoms nuclei and semiconductor devices , After solving this question paper students can notice his preparation for class 12th CBSE (Board examination ).

    To get the question paper related to this topic click here-

    PHYSICS CLASSES BY NAYAN JHA
    Test class 12th
    ( Dual nature, Atoms and Nuclei and Semiconductor)
    Sec-A ( each questions carry 2 marks)
    1.Define the term threshold frequency and stopping potential in relation to the
    phenomenon of photoelectric effect . how is photoelectric current affected on increasing
    the (I) frequency (II) intensity of the incident radiations and why?

    1. Draw the graph showing the variation of potential energy between a pair of nucleons as a
      function of their separation. Indicate the regions in which the nuclear forces is (i) attractive,
      (ii) repulsive. Write two important conclusions which you can draw regarding the nature of
      the nuclear forces.
    2. Distinguish between conductors, insulator and semiconductors on the basis of their
      energy bands.
      Or,
      State the reasons, why GaAs is most commonly used in making a solar cell.
      Sec-B (each questions carry 3 marks )
    3. An electron of mass m and charge q is accelerated from rest through a potential
      difference V , obtain the expression for the de-Broglie wavelength associated with it . if electron and proton are moving with the same K.E. , which one of them will have a large De-Broglie wavelength associated with it ? give reason .
    4. State any two postulates of Bohr theory of hydrogen atom . what is the maximum
      possible no. of spectral lines observed when the hydrogen atom is in its second exited state? justify your answer . calculate the ratio of the max. and min. wavelength of the radiation
      emitted in this process.
    5. Using Bohr postulates for hydrogen atom , show that the total energy of the electron in
      the stationary states can be expressed as the sum of kinetic energy(K) and potential energy
      (U) , where K=-2U. hence , deduce the expression for the total energy in the nth energy level
      of hydrogen atom .
    6. Draw the binding energy per nucleon curve . using the curve state clearly how the release
      in energy in the process of nuclear fission and nuclear fusion can be explained.
    7. The energy level diagram of an element is given below . identify using necessary
      calculations , which transition corresponds to the emission of the spectral line of
      wavelength 102.7 nm . which transition corresponds to the emission of radiation of
      maximum wavelength?
      .
    8. (i)Define the activity of the radioactive material and write its SI unit. plot a graph showing
      the variation of activity with respect to time of a given radioactive sample.(ii) what is meant
      by half life time of a radioactive element ? the half life of a radioactive sample is 30s
      calculate (a) the decay constant and (b)time taken for the sample to decay by 3/4thof the initial value .
    9. Explain, with the help of a circuit diagrams, the working of a photo-diode. Write briefly
      how it is used to detect the optical signals.
      Or
      a) How is photodiode fabricated
      b) Briefly explain its working. Draw its V-I characteristic for two different intensities of
      illumination.
      Sec –c ( case study based questions)
    10. Line spectra of the hydrogen atom –The spectral series of hydrogen atom were accounted for
      by the Bohr using the relation 1/ʎ = R(1/n1-1/n2). Where R is the Rydberg constant . Lyman series is obtained when an electron jumps to first orbit from any subsequent orbit . Similarly Balmer
      series is obtained when an electron is jumps to 2nd orbit from any subsequent orbit . , Paschen series is obtained when an electron is jumps to 3rd orbit from any subsequent orbit. Whereas
      Lyman series is lies in U.V. region , Balmer series in visible region and Paschen in infrared region.
      Series limit is obtained when n2=infinity.
      1.The wavelength of first spectral line of Lyman series is.(a) 1215.4 A (b)1215.3cm (c)1215.4m
      (d)1215.4mm.
      (ii)The wavelength limit of Lyman series is (a)1215.4 A (b)511.9A (c)951.6A (d)911.6A
      (iii) The frequency of spectral line of Balmer series is (a) 1.097 x 107 Hz (b) 4.57x1014A (c) 4.57 x
      1015Hz (d)4.567 x 1016Hz
      (iv)Which of the following transition in hydrogen atoms emits photons of highest frequency (a)
      n=1 to n=2 (b) n=2 to n=6 (c) n=6 to n=2 (d)n=2 to n=1 .
      (v) The ratio of minimum to max wavelength in Balmer series is (a) 5:9 (b) 5:36 (c) 1:4 (d)3:4 .

  • Test paper of Dual nature of matter and atoms and nuclei

    This test paper d contain the questions of chapter, Dual nature and atoms and nuclei . Having completed these chapter students must try to solve this question paper. Provided by Nayan jha.

            Physics classes by Nayan jha                       

                        Test class 12th

                       (   Dual nature , Atoms and nuclei )

    1. Draw a suitable graph to show the variation of photoelectric current with collector plate potential for (i) a fixed frequency but different intensities , I1>I2 > I3 of radiation .(ii) a fixed intensity but different frequencies v1 > v2 > v3 of radiations.         [2marks]                                                                            2. Using De- Broglie hypothesis explain with the help of suitable diagram , Bohr’s second postulates of quantization of energy in hydrogen atom ..                               [2-marks]                                                                                                                                                  3. Show that the density of nucleus over a wide range of nuclei is constant independent of mass number A.                                                                                                                                         [2marks]                                                                                  4. An electron of mass m  and charge q is accelerated from rest through a potential difference V  , obtain the expression for the de-Broglie  wavelength  associated with it . if electron and proton are moving with the same K.E. , which one of them will have a large De-Broglie wavelength associated with it ? give reason .                                                                 [3-marks]                                                                                                                                                            5. Using Bohr postulates for hydrogen atom , show that the total energy of the electron in the stationary states can be expressed as the sum of kinetic energy(K) and potential energy (U)  , where K=-2U. hence , deduce the expression for the total energy in the nth energy level of hydrogen atom   .                                                            [3-marks]                                                                                                            6. . The energy of an electron in the ground state of hydrogen atom is -13.6 Ev. (i) what does the negative sign signify ? (ii)how much energy is required to take an electron in this atom from the ground state to the first exited state?                                                                             [3-marks]                                                                                                                                                                                                                                       5.( Case  study based question)  Photoelectric effect is the phenomenon of emission of electrons from a metal surface , when radiation of suitable frequency fall on them . The emitted electrons are called photoelectrons and the current so produced is called photoelectric current.                [5-marks]                                                                                                              i. With the increase of intensity of incident radiation on photoelectrons emitted by a photo tube , the number of photoelectrons emitted pre unit time is (a) increases (b) decreases (c) remain the same  (d) none of these   ii. It is Observed that photoelectrons emission stops at a certain time t after the light source is switched on . The stopping potential can be represented as (a) 2(K.E.)max/e (b) (K.E.)max/e  (c) (K.E.)max/3e (c) (K.E.)max/2e .                                   

      iii. A point source of light of power 3.2×10-3 W mono energetic photons of energy 5.0eV and work function 3.0eV . The efficiency of photoelectrons emission is 1 for every 106 incident photons . Assume that the photoelectrons are instantaneously swept away after emission . The max kinetic energy of photon is (a) 4eV (b) 5eV (c) 2eV (d) Zero .                                                                                                               

     iv. Which of the following is the application of photoelectric effect ?   (a)L.E.D  (b)Diode (c) Photocell     (d) Transistor .                                                                                                               

       v. If the frequency of incident light falling on the photosensitive metal is doubled , the kinetic energy of the emitted photoelectrons is (a) Unchanged (b) halved (c) doubled (d) more than twice its initial value.

  • test paper for class 11th

    test paper for class 11th

     test paper for class 11th

    this test paper specially design for the students of class 11th( physics) . this question paper covers questions from chapter 1st to chapter 6th . student can check there preparation using this test paper . this question paper also contain very important questions , so  students must try to solve these question  test paper for class 11th.

    projectile

                                                            Test -11th

    M.M.-30                                                                                                      TIME-1:00  

    All questions are compulsory , section- A contains 5 questions each carry 1 mark, section- B contains 7 questions each carry 2 marks ,section- C contains  12 questions each carry 3 marks , section-D  contains 3 questions each carry 5 marks.

      SECTION (A )                                                                                                                               

    1. The volume of an object as a function of time is calculated by where t is time in seconds and v is in cubic meter. Determine the dimensions of constants A and B.

     

    1. A stone is thrown such that its horizontal range is 4 times the maximum height. Find the angle of projection.

     

    1. A cricket ball of mass 150 g has an initial velocity m/s and final velocity  m/s after being hit. Calculate the change in momentum.
    2. What happens to coefficient of friction when the weight of a body is doubled ?
    3. If a man in an elevator drops his briefcase but it does not fall to the floor, what can you conclude about the elevator’s motion?

     

    SECTION-B

     

    1. When a particle rotates in a circle, a central force acts on it directed towards the center of rotation. Why does this force does no work on the particle?
    2. A cubical block rests on a plane of coefficient of friction √3. The angle through which the plane be inclined to the horizontal so that the block just slides down will be what? Also define angle of repose.
    3. Show that the path followed by the particle given angular projection is parabolic.
    4. If a projectile is projected with same initial velocity at two different angles α and β with the horizontal , if horizontal distance covered in both the cases are same thin find the ratio of there maximum height attained in both cases.
    1. The block of mass M moving on the frictionless horizontal surface collides with the spring of spring constant k and compress it by length L. Calculate the maximum momentum of the block after collision.               
    1. Explain impulse-momentum theorem. Give some practical applications of impulse.
    2. State and explain work energy principle using calculus method.

             SECTION-C

    1. The displacement of a body is proportional to t3, where t is time elapsed , then what will be the nature of velocity-time and acceleration – time graph. Also plot the position time graph for the uniform motion of an object along a straight line , if (i) x0=positive , v=negative and magnitude of velocity is constant (ii) both x0 and v are negative  and magnitude of velocity is constant.
    1. Explain Parallax method, how it is used to find the radius of the planet ?
    1. The escape velocity v of a body depends on the (i) acceleration due to gravity,(ii)the radius R of the planet. Establish dimensionally the relation for the escape velocity. Also write the dimension of gravitational constant G.
    1. Define acceleration due to gravity. Obtain relations to show how the value of ’g’ changes with (i) altitude , (ii) depth .

     15. state and derive Kepler’s laws of area and periods for circular orbits.

    1. A man can jump 1.5 m on earth . calculate the height he may be abled to jump on a planet whose density is one quarter that of earth and whose radius is one third that of earth.

     19.A uniform circular disc of radius R is rolling on a horizontal surface . Determine the tangential velocity (i) at the upper most point ,(ii)at the center of mass and (iii) at the point of contact. 

    1. A body is moving with uniform acceleration , its velocity after 5 sec is 25m/s and after 8 sec is 34m/s. calculate distance it cover in 15th sec .
    1. A pump on the ground floor of a building can pump up water to fill a tank of volume 30 m3 in 15 min. If the tank is 40 m above the ground , how much electric power is consumed  by the pump , the efficiency of the pump is 30%.

     22.Define spring constant , write the characteristics of the force during the elongation of the spring . Derive the relation for the potential energy stored when it is elongated by the distance X .

    1. (i) A light and heavy body have same kinetic energy , which of the two have more momentum and why? (ii) If kinetic energy of a body is increased by 300% , find the % increase in its momentum.
    1. Two blocks of mass 2kg and 5kg are connected by a light and inextensible string passing over a frictionless pulley . the block of mass 2 kg is free to slide on a surface inclined at an angle of 300 with the horizontal whereas 5 kg block hangs freely . find the acceleration and tension in the string.

     SECTION-D

    1. What do you mean by Banking of roads. What is the need of banking a circular road. Discuss the motion of car on banked circular road(with friction).

    A vehicle running with speed 72 km/hr applies brakes producing a retardation of 3 m/s2 while taking a turn of radius 100 m. Find the acceleration.

    1. State and prove the theorem of (i) parallel axis and , (ii) perpendicular axis . Also  find the moment of inertia of a circular disc about the axis perpendicular to the plane and passing through the center .
    1. How does a perfectly elastic collision is different from perfectly inelastic collision ? Two particles of mass m and M having velocities u1 and ­u­2 respectively make an head on collision .Derive the relation for their final velocities . discuss the following special cases (i)m=M (ii) m>M and  u2=0