Physics Classes

Category: Assignments

  • Most important numerical of electrostatics

    Important numerical of electrostatics  ( Top 12 )

    This assignment contain top 12 important numerical  of electrostatics , chapter 1 and 2 (unit-1). Students preparing for 12th board examination included all states and ICSE board ( even students preparing for JEE/NEET) must solve these numerical.

    1. (i)Two point charges 4Q and Q are separated by 1m in air at what point on the line joining the two charges the electric field intensity is zero. (ii) Two identical metallic sphere A and B having charges +4Q and -10Q are kept at a certain distance apart . A third identical uncharged sphere C is first placed in contact with sphere  A and then with sphere B . Spheres A and B are then brought in contact and then separated . Find the charges on the sphere A and B . 

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    2. (i) Calculate the amount of work done in turning an electric dipole of dipole moment 3×108 C-m from its position of unstable equilibrium to stable equilibrium, in a uniform electric field of intensity 103N/c. (ii)The electric field components due to a charge inside the cube of side 0.1m are shown below      Ex=αx   ,  where α =500N/C-m EY=0,EZ=0

    Calculate (a) The flux through the cube (b)the charge inside the cube

    3.(a) A uniformly charged conducting sphere of 2.5 m in diameter has a surface charge density of 100µC/m2 . Calculate the  (a) charge on the surface  and (b)Total electric flux through the surface. (b)Two large, thin metal plates are parallel and close to each other.  On their inner faces, the plates have surface charges densities of opposite signs and of magnitude 17.0 x 10-22 C/m2.   What is electric field strength E:  (a) in the outer region of the first plate, (b) in the outer region of the second plate, and (c)  between the plates?

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  • Top 20 questions for class 11th first term examination

    Top 20 most important questions for class 11th first term examination.

    This assignment contain 22 most important questions for class 11th first term examination, from unit-1 to unit- 7 (gravitation) . this assignment contain the questions based on derivation only (for important numerical you have to see another assignment).

    1. What is dimensions? What are the uses of dimensions on the basis of their uses answer the following questions.

    (a) If (p+ a/V2) (V-b)=RT where the symbols has their usual meanings, then what is the dimension of a/b . (b)  If   F= a/ b+√d , where f=force ,d= density  , then find the dimension of a and b.(c ) The factors effecting the time period (T) of the  simple pendulum depends on mass , length and acceleration due to gravity . Deduce the relation for time period of the simple pendulum.

    2.  (i) Draw velocity -time graph of uniformly accelerated motion in one dimension .From the velocity time graph of uniform Accelerated motion ,deduce the equations of motion in using this graph (or using calculus method). (ii) A ball is thrown vertically upwards. Draw its:  (i) Velocity-time curve (ii) Acceleration-time curve, If T is the time of flight. Using calculus method also find the distance covered in nth second.

        3.  Define average velocity and relative velocity. A car travels first half of a length S with velocity u1. The second half is covered with velocities u2   and u3 for equal time intervals .Find the average velocity of the motion. Also answers the following questions (a)  A body start from rest and accelerates uniformly .find the ratio of the displacement in, (1)one, two and three seconds, (2) first ,seconds and third second. (b). A body covers 12 m in 2nd seconds and 20 m in 4th seconds .find what distance the body will cover in 4 second after 5th second.

    4.State the triangle law and parallelogram law of vector addition, derive the expression for the magnitude and direction of the resultant of two vector. (**Also solve some numericals based on this derivation).also write the answers of the following questions

     (a) If a man can swim with speed s in still water , if a river flowing with speed v from east to west , find the(1) velocity of swimmer with respect to river ,(2) in which direction should he swim to reach the opposite direction (3) what is the minimum time taken by the swimmer to reach on opposite bank if width of the river is ‘d’.

     (b)   Rain is falling vertically downward  with speed Vr , and a man is running on the horizontal road with speed Vm , in which direction should he hold his umbrella to protect him from rain.

    5. A projectile is fired at an angle θ with the horizontal . (a) show that its trajectory is parabolic, (b) Obtain the expression for , time of flight ,horizontal range and vertical height. A body is projected horizontally from the top of a building  of height H , if velocity of projection is  ‘u’ find (a) time it will take to reach the ground (b)horizontal distance from the foot of the building where it will strike the ground, and (c) velocity with which body strikes the ground. Also answer the following questions (i)at what value of  θ  the range will be maximum, ((ii)) prove that for a given velocity of projection the horizontal range is same for θ and 90- θ .

    6. Define centripetal acceleration and centripetal force find the expression for it if a body of mass m moving with a uniform speed u in a circular path of radius r (derivation of centripetal acceleration).

    7. Answer the following questions (a)  State, Newton’s second law of motion. show that second law is the real law of motion .(b) If a man of mass m is in a lift find the apparent weight of the man when (i) lift is accelerating upward with acceleration ‘a’, (ii)lift is accelerating downward with acceleration ‘a’ , (iii) lift is moving upward with constant velocity v ,(d) lift is falling freely under gravity.(c)Explain, Why pull is easy as compared to push a rolling body ?

    8. Distinguish between static friction , limiting friction and kinetic friction,  haw do they vary with the applied force , explain with the help of a diagram. . (b)write the laws of limiting friction (c)Why are ball bearings used in machinery? (d) What is the need of banking of road. (e) State two advantage and disadvantages of  friction.(d) Explain why (i) a cyclist slow dawn his speed while taking turn. (ii) a cyclist bend himself towards the centre at the turn . (iii) it is necessary of banking of road ?

    9. Define impulse .(a) A cricket ball of mass m moving with speed of v m/s, calculate the impulse received by the ball (b) a ball moving by a momentum of strike against a wall at an angle of  θ with the normal and is reflected at the same angle and with the same speed . find the change in momentum of the ball.

    10. Define conservative and non- conservative force.  How will you find variable force ? what is the significance of F-x graph.?  Explain conservation of energy ,draw a graph showing the variation of potential and kinetic energy with respect to the height of a  free fall under gravity.

    11. Define elastic and inelastic collision . discuss elastic collision in one dimension . obtain expression for velocities of two bodies after such a collision .Also show that for perfactaly elastic collision coefficient of restitution is 1.  

    12. State and explain work energy theorem.Also Find the relation between kinetic energy and linear momentum . using this relation answer the given questions, (a) two bodies of masses M  and m (M>m)having same momentum , which has more kinetic energy? (b)  ) two bodies of masses M  and m (M>m)having same kinetic energy, which has more momentum? (c)the linear momentum of a body is increased by 10% what is the % change in kinetic energy? (d) the kinetic energy of  a body is increased by 10% what is the % change in linear momentum?

    13 . Find  the expression for the potential energy stored in a  stretched spring of spring constant    K  and it is stretched by distance X. Also plot the graph which shows the variation in kinetic energy and potential energy  with respect to X if spring is free to oscillate.

    14.State Newtons law of gravitation in vector form .(I)Haw can you find the mass of earth ,starting from the law of gravitation?)II) What are the factors affecting the value of G  ? (III)If mass of two bodies are doubled and distance is halved , how will the gravitational force change ? Write the differences between (I) Inertial ang gravitational mass,(II) G and g (III)escape velocity and orbital velocity on earth.

    15. Define gravitational acceleration , find the expression for it, also find its value on the surface of earth .Haw the value of g changes (I) With altitude (II)with the depth .A planet reduces its radius by 1% with its mass remaining same , haw acceleration due to gravity changes ? Find the relation between height h above the earth surface with the depth from the earth surface where the value of g will be same.

    16. what is geostationary satellite  ? calculate the height of the  orbit above the surface of the earth in which a satellite is placed , will appear stationary, and also write the conditions for the launching of  geo stationary satellite .Also, define the term orbital velocity , find the expression for (a) orbital velocity(b) time period and(c) total energy of the satellite . Obtain the relation for orbital speed and escape velocity of the satellite from earth surface.

     17. Answer the following questions-(a) what is the percentage increase in velocity for moon to escape from the gravitational pull of the earth ?( b) If the earth supposed to be a uniform sphere , suddenly contract and its radius becomes half of its original value , what will be the duration of day (or what will be time of rotation of earth on its own axis/ what will be the %change in duration of day)?( c)Why space craft usually launched from west to east ? why is it more advantageous to launch rockets in the equatorial plane?(d) What is escape velocity ? obtain the expression for the escape velocity on earth . why there is no atmosphere on moon? Explain. Also state and prove Kepler’s laws of planetary motion.

    18. Answer the following questions, (a)Is it possible to open a pen cap with one finger? Why? (b)When a sphere, ring, disc and spherical shell are coming down on an inclined plane, rolling without slipping, which will reach the ground first?( c)How will you distinguish between a hard-boiled egg and a raw egg by spinning each on a table top?(d)What is torque? Write its formula in vector form. Handle, to open the door, is always provided at the free edge of a door. Why? ( e)If earth were to shrink suddenly, what would happen to the length of the day?

    19. Answer the following questions                                                                                                                                                                  (a)Derive the relations (i)L = I ω    (ii) Ʈ =  Iα (b)If angular momentum is covered in a system whose moment of inertia is decreased, will its rotational kinetic energy to be also conserved? Explain.                      ( c)Can a body in translatory  motion have angular momentum? ( d)Explain.Write an expression for the moment of inertia of a circular disc of a mass M and radius R(i)about an axis passing through its centre, and a perpendicular to its plane.(ii) about its diameter.(iii)about a tangent to its own plane.(iv) about a tangent perpendicular to the plane of the disc.

          20. Obtain an expression for position vector of centre of mass of a two particle system. From a     uniform circular disc of diameter d , a circular hole of diameter d/6 and having its centre at a distance of d/4  from the centre of the disc is scooped out , find the centre of mass of the remaining portion .

    21. What is the difference between rotational kinetic energy and rolling kinetic energy?Show that rolling kinetic energy of a rolling body is given by 1/2mv2(( K2/r2)+1) , where r is the radius of the body and K is the radius of gyration of the body. How much fraction of the K.E. of rolling is purely (i) translational (ii) rotational ?

    22.(i) Define moment of inertia and radius of gyration also write the parallel and perpendicular axis      theorem.(ii)Derive an expression for moment of inertia of a disc of radius r, mass m(iii)Derive an expression for moment of inertia of a thin circular ring passing through the centre and perpendicular to the plane of the ring.

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  • Assignment current electricity

    This assignment contain all important questions of chapter current electricity.

    1. How does the drift velocity of electrons in a metallic conductor very with increase in temperature ?                               2.The metallic conductor is at a temperature  θ1 .The temperature of the metallic conductor is increased to θ2 How will the product of its resistivity andconductivitychange?                                                                                 3. A cell of e.m.f. 2 V and internal resistance 0.1 Ω is connected to a 3.9 Ω external resistance .What will be the p.d. across the terminals of the cell 4.Nichrome and copper wires of the same length and same radius are connected in series .Current I is passed through them .Why does the nichrome wire get heated first ?                                       5. Sate the condition in witch terminal voltage across a secondary cell is equal to its e.m.f.                                                                 6. Two bulbs whose resistances are in the ratio of 1 ; 2, are connected in parallel to a source of constant voltage . What will be the ratio of power dissipation in these?                                                                                                            7. A toaster produces more heat than a light bulb when connected in parallel to the 220 V mains. Which of the two has greater resistance ?      

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  • Very important numerical of magnetic effect of current

    Very important numerical of magnetic effect of current

    This blog contain very important numerical of magnetic effect of current. There are 10 numerical based on this chapter. It is not necessary that questions will be asked from this blog same as given questions, but these questions will help you to improve your numerical skill . Students preparing for class 12th board exam must solve these questions, i am sure it will help you to improve and sole numerical question of this chapter.

    1. Two wires A and B have the same length equal to 44cm . and carry a current of 10A each . Wire A is bent in circle and B as a square .(a) obtain the magnetic field by both the coils at the center ,(b) which has more field at their centre?

    2. A straight long thick  wire of uniform cross-section ( radius  r=10cm ) carries current 10A through it . Calculate the ratio of magnetic field at a point  r/2 above the surface and a point r/2 below the surface. What is the maximum field due to this current carrying wire?

    To download the 10 very important numerical-ch-4 click hereDownload

  • Test NEET /JEE Chapter 1 -4 (class 11th)

    ( chapter 1 -4 class 11th)

    There are 20 questions in this question paper. Students have to solve it in 25 minutes only .

    Test NEET/JEE (ch-1,2,3,4)

    1. A  new system of units is proposed in which unit of mass is A kg . unit of length is B kg and unit of time is C s , What will be the value of 5 j in new system?

    (a) 5AB2C-2 (b) 5A-1B-2C2 (c) 5 A-2 B-1 C-2 (d) 5 A-1 B-1 C2

    2. If linear momentum P , area A and  time t is taken as fundamental units then the dimensional formula of  energy is (a) P1 A-1 t-1  (b) P2 A1 t1   (c) P1 A-1/2 t1   (d) P1 A1/2 t-1.

    3.  If E , m,L  and G denotes energy , mass , length and gravitational constant then the ( EL2 /m5G2) has the dimension of   (a) mass (b) length (c) time (d) angle.

    4. The period of oscillation of time period T is 2π(l/g)1/2 measured value of l is 10 cm is known as 1mm accuracy ant time for 100 0scillations of the pendulum is found to be 50 s using a wrist watch of 1s resolution . What is the accuracy in the measurement of g ?

    (a)2% (b) 3% (c) 4% (d) 5% .

    5. Two resistors of resistance R1=100+-3 Ohm R2=200+-4 Ohm then the equivalent resistance of parallel combination is (a) 66.7 +-1.8  (b) 66.7+- 4  (c) 66.7+-3  (d)66.7+-7 Ohm.

    6. A cube has a side of length 1.2 x 10-2 its volume upto correct significant figure is (a) 1.7×10 -6 (b) 1.73×10 -6 (c) 1.78×10 -6(d) 1.732×10 -6.

    7. T he position of the object moving along x-axis is given by x= a+bt2, where a=8.5 b=2.5 and t is measured in seconds. The average velocity of the object between t=2s to t=4 s  in m/s  is (a) 5 (b) 10 (c) 15 (d) 20 .

    8. A player throw a ball vertically upwards with velocity u at highest pint , (a) both velocity and acceleration are zero (b) The velocity of the ball is u and acceleration is zero (c)The velocity of the ball is 0 but acceleration is g (d) the velocity of the ball is u and acceleration is g .

    9. If a lift is moving upward with velocity 5m/s a girl throw a ball upward with speed 50m/s the ball will returns on her hand in time (a)5s (b)10s (c) 15s (d) 20s.

    10. A boy sliding on the smooth inclined plane requires 4 s to reach on the ground starting from rest from the top . How much time will it take to cover one fourth the distance starting from rest at the top?

    (a) 1s (b) 4s (c)2s (d)16s .

    11. A particle is released from rest from a tower of height 3h . the ratio of the intervals of time to cover three equal heights h is (a) t1:t2: t3 = 3:2:1 (b) t1:t2: t3 =1: (√2-1)(:√3-2) (c) t1:t2: t3 =√3:√2:1 (d) t1:t2: t3 = 1:√2-1): (√3-√2).

    12. A ball A is thrown upward  with velocity u  at the same time another ball B is released from rest at height H,  at time t the speed of A relative to B is (a) u (b) u-2gt (c) (u2-2gh)1/2 (d)u-gt.

    13. A vehicle travel half the distance L with speed V1 and other half with speed V2 then its average speed is , (a) (V1 + V2)/2 (B) (2V1+V2)/V1+ V2 (C) 2V1V2/V1+V2 (D) L(V1+ V2)/V1V2 .

    14. Two vectors    and A+B = C then A and B are (a) parallel (b) perpendicular (c) anti-parallel (d) null vector.

    15. If resultant of two equal vectors is equal to the either forces Then the angle between these two vectors is ,(a) 900 (b) 1200 (c) 600 (d) 300

    16. if dot product  of two vectors   is null vector then the angle between these two vectors is   (a) 0 (b) 1200 (c) 900 (d) 450 .

    17. If  then  then which of the following statement is  correct ( a) vector A is perpendicular to  vector B (b) vector A is parallel to vector C (c) vector b is parallel to vector C (D) vector A is perpendicular to vector C .

    18.Two vectors  magnitude of A,B and C are 3,5,4 respectively then  (a)the angle between A and B is 900 . angle between A and C is 900. (c) angle between B and C is 900(d) angle between A and B is 00.

    19. If unit vector of a vector is represented as 0.5  – 0. 8  +c  then the value of c is (a) √0.01  (b) √0.11  (c) √0.39 (d)  1.

    20. The component of a vector A is along X-axis will have maximum value if (a)vector A is along positive Y axis   (b)vector A along positive x-axis  (c) vector A makes angle 450 with the x-axis  (d) A is along negative X aixis.

  • Test solid, liquid and gases incluting thermal properties of matter

     Solids, liquid and thermal properties of matter.

    1. The maximum load a wire can withstand without breaking, when its length is reduced to half of its length, will (i) be doubled (ii) be half (iii) be four times (iv) remain same .                                                           2. If length of a wire is doubled and area is halved then its young modulus will be (i) same (ii) halved (iii) four times (iv) ¼ times.                                                                                                                                                            3.The two ends of the wire maintained at temp. 100 and 1100c the rate of flow of heat is 4j/s . if the temp. of the ends are 200 and 2100c then the rate of flow of heat will be (i) 16.8 (ii)8.0 (iii)4.0 (iv) 44.8 j/s.                                                                                                                                                                                                      4. An ideal liquid flows through a tube having diameters 2.5 and 3.75 cm then the ratio of velocity of liquid through these cross-section is (i)9:4 (ii)3:2 (iii) (3/2)1/2.(iv) (2/3)1/2                                                                              5. If volume of a system is doubled without changing its temp then volume will be (i) doubled (ii) same (iv) four times (iv) halved.                                                                                                                                                              6. Two moles of helium gas undergo a cyclic process as shown in fig. assuming the gas to be ideal calculate the following quantities in the prosses (a) the net work done (b) the net change in internal energy (c) the net change heat energy. (R=8.32j/mole)

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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

  • Hots questions based on semiconductor

    Hots questions based on Semi conductors.

    These questions are important for class 12th board Examination.

    Q. 1. What are different types of compound semiconductors? Give two examples of each.

    Ans- The compound semiconductors are of following types

    • Inorganic semiconductors: Cds, GaAs, CdSe
    • Organic semiconductors: Anthracene, pthalocynines
    • Organic polymers: Polyparrole, polyaniline, polythiophene.

    Q. 2. Which characteristic of a semiconductors make them useful in fabrication of electronic devices?

    Ans- The number of charge carriers and their direction of flow can be controlled within the solid semiconductor.

    Q. 3. Give three advantages of semiconductor devices over conventional vacuum tube devices.

    Ans- 1. The charge carriers can be manipulated within the semiconductor unlike the vacuum tubes where the electrons were manipulated in vacuum.

    2. The size of semiconductors devices is very small because they do not require vacuum for manipulation of the charge carriers.

    3. The semiconductor devices consume lesser energy because unlike vacuum tube, they do not require heating for electron emission.

    Q. 4. What are the characteristics to be taken care of while doping a semiconductor? Justify your answer.

    Ans-(i) The number of dopant atoms should be small and restricted to just a few parts per million (ppm) of the pure semiconductor atoms.

    (ii) The size of the dopant atom used should be nearly equal to that of the semiconductor atom.

    The above characteristics are essential so that the doping process does not cause any major distortion in the original pure semiconductor lattice. The dopant atom just substitute some of the semiconductor atoms in their lattice.

    Q. 5. Give example of the dopants used to make

           (i) n-type semiconductor                       (ii) p-type semiconductor.

    Ans- n-type semiconductor are formed by using pentavalent impurity e.g. Arsenic (As);  Antimony (Sb), Phosphorous (P) p-type semiconductors are formed by adding trivalent impurity to pure semiconductor e.g., Indium (In), Boron (B), Aluminium (Al).

    Q. 6. What is the energy required to make electrons free for conduction in pure (i) germanium (ii) silicon? How does the energy value change in a doped semiconductor?

    Ans- In a pure semiconductor, the energy required to make electrons available for conduction is large. It is about 0.72 eV for germanium and about 1.1 eV for silicon. In doped germanium, the energy required becomes nearly 0.01 eV and in doped silicon it is about 0.05 eV.

    Q. 7. What is the net charge on a p-type extrinsic semiconductor? Justify.

    Ans- Zero, the crystal maintains its overall neutrality because the charge on additional charge carriers is just equal and opposite to that of the ionised cores in the lattice.

    Q.8. What should be the value of the reverse breakdown voltage of the diode used in a half-wave rectifier and why?

    Ans- The reverse breakdown voltage of the pn-junction diode used in half-wave rectifier should be higher than the peak voltage of the a.c. voltage at the secondary of the transformer. The condition is necessary to protect the pn-junction diode from reverse breakdown.

    Q.9. How is a sample of n-type semiconductor electrically neutral though it has an excess of negative charge carriers?

    Ans- n-type semiconductors are fabricated by adding group 15 impurity atom which are neutral and having one extra proton for every conduction electron. So the sample in neutral.

    Q.10. A student has to study the forward and reverse characteristics of a pn-junction. What kind of circuit arrangement should he use?

    Draw the typical shape of input and output characteristic curves likely to be obtained.

    Mark the knee voltage and reverse breakdown voltage on the curve. How can the static and the dynamic resistance be determined from the curves?

    In which of the regions does the pn-junction remain when used as (i) full-wave rectifier (ii) stabiliser?

    Q.11. What do you mean by host atoms in semiconductors?

    Ans- In impure semiconductors, the semiconductors atom (e.g. Ge or Si) are called host atoms.

    Q.12. What are optoelectronic devices? Give any two example of such devices.

    Ans- The semiconductor junction diodes in which the charge carriers are generated by photons are called photoelectronic devices. The examples of such devices are

    • Photodiodes
    • Light emitting diodes
    • Photovoltaic or solar cells.

    Q.13. Two semiconductor pieces X and Y of same length and equal area or cross-section are provided. One of the materials is pure semiconductor and the other is doped.

    (i) How will you identify the impure semiconductor from the two give pieces X and Y?

    (ii) For a given rise in temperature what will be the relative charge in the behaviour of the two materials?

    Ans- (i) Measure the electrical resistance offered by X and Y. The piece offering lower resistance will be impure semiconductor.

    (ii) Both X and Y will have negative temperature coefficient of resistance. However, the resistance of pure semiconductor will decrease sharply with rise in temperature as compared to the impure semiconductor.

    Q.14. A photodiode is operated is reverse bias region only although the forward current is known to be more than the current in reverse bias. Give reason.

    Ans- A photodiode is sensitive to light and is used to measure/detect intensity of light incident on it. In a pn-junction, photodiode; consider n-type region. The electrons in this region are majority carriers and the holes are minority charge carriers

    ؞                              ne >> nh.

    When the pn-junction is illuminated the bonds between same atoms breaks up due to photo-excitation leading to increase in ne and nh say by ∆ne and ∆nh

    We have                       ∆ne = ∆nh

    ؞                                    ∆nh/nh >>  ∆ne/ne

    i.e. The fractional increase in minority charge carriers is very large as compared to that in minority charge carriers.

    The current through pn-junction in reverse bias is due to drift of the minority charge carriers. The number density of minority carriers being sensitive to light intensity; the reverse current show a rapid change with intensity of incident light.

    So a photodiode is always operated in reverse bias.

    Q.15. What is the minimum frequency that can be detected by a photodiode?

    Ans- The minimum frequency (vm) that can be detected by a photodiode depends on the energy gap Eg of the semiconductor and is given by

                                H vm = Eg

        ؞                         vm = Eg/h.

    Q.16.What are the factors taken into consideration while selecting material suitable for fabrication of solar cell?

    Ans-The following factors are taken into consideration while fabricating solar cell:

    • Band gap is 1.0 eV to 1.8 eV
    • High optical absorption
    • Reasonable electrical conductivity
    • Availability of raw material
    • Cost.

  • Important questions of physics (Term-2)

    Important questions of class 11th [physics (Term-2)]

    This assignment contain the questions of following chapters [ 1- Solids ( elasticity), 2- Fluids , 3- Thermal properties of matter, 4- Thermodynamics,5-Oscillations ,6-Waves ]

    1 .What are the basic assumptions of kinetic theory of gases? on their basis, derive an expression for the pressure exerted by an ideal gas.

    2. What is meant by degrees of freedom? State the law of equipartition of energy. Hence calculate the values of molar specific heats at constant volume and pressure for monoatomic, diatomic and triatomic gases.

    3. Calculate the kinetic energy of one mole of argon at 127⁰C. given that N =6.02×1023 mol and k=1.381 x10-23 mol-1K-1

    4.Calculate the number of degrees of freedom for one mole of diatomic gas at N.T.P

     5.Calculate the number of degrees of freedom of 1 cm3 of helium gas at N.T.P.

     6.A vessel contains argon gas at 127⁰C. find the average kinetic energy of argon molecule, if      Boltzmann’s constant, k=1.38 x 10-23 j mol -1 K-1 .

    7.Calculate the total kinetic energy of 1g of helium at 27⁰C Given that R =8.31 mole -1 K-1.

    8.At what temperature is the r.m.s velocity of a hydrogen molecule equal to that of a oxygen molecule at 47⁰C ?

    9.Give the kinetic interpretation of temperature and define absolute temperature.

    10.If three molecules have velocities 0.5,1 and 2km s-1 respectively, calculate the relation between the root mean square speed and average speed.

    11. Calculate the temperature at which the r.m.s velocity of a hydrogen will be equal to 8km/hr. given that R =8.31 j mole -1.

    12. Calculate the r.m.s velocity of CO2 molecules at N.T.P. given, R=8.31 j mol -1 K-1 .

    13. Calculate the r.m.s velocity of hydrogen at N.T.P. given that density of the gas is 9×10-5 g cm -3.

    14.Find the temperature at which the root mean square velocity of a gas is double than that its value at 0 ⁰C , pressure remaining constant.

    15. The molar gas volume at S.T.P. is 22.4 litre and Avogadro number is 6.023×1023. (a) calculate the number of gas molecules per unit volume,

    16. Draw a graph to show the variation of V2 rms  with absolute temperature .

    17. When an ideal gas undergoes an isothermal expansion, the pressure of the gas in the encloser falls. Why?

    18. Two identical cylinders contains helium at 2.5 atmosphere and organ at 1 atmosphere. Find pressure if both the gases are filled in one of the cylinders?

    19. The temperature of argon, kept in vessel, is raised by 1⁰C at constant volume. The total heat supplied to the gas is a combination of translational energies. Find their respective shares.

    20. A gas mixture consist of 2moles of oxygen and 4 moles of argon at temperature T. find total internal energy of the system, when vibrational modes are rejected.

    21.During an adiabatic process, the pressure of a gas is found to be proportional to cube of its absolute temperature what is the ratio of Cp/Cv ?

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    TERM-2-Important-questions-of-class-11thDownload

  • Important questions of oscillations

    Important questions of oscillations-

    1. What is meant by periodic and oscillatory motion? Distinguish between them.

    2. What is meant by SHM . Find the expressions for displacement , velocity and acceleration. Also find the phase difference between them.

    3. Find the potential energy and kinetic energy of a SHM and hence show that total energy is conserved . In what position of the oscillation is the energy wholly kinetic and wholly potential?

    4. Prove that for an harmonic motion time period T = 1/2π(spring factor/inertial factor)1/2.

    5. What is simple pendulum? Derive expression for the time period or frequency of the oscillating simple pendulum. Also explain the second pendulum and find the length of the second pendulum on the surface of earth.

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    6. Show that vibration of the liquid in the U-Tube is simple harmonic and also find the expression for the time period and frequency .

    7. Explain the term (i) Free vibration (ii) Forced vibration (c) Resonant vibration (d) Damped oscillation.

    8. A cylinder floating in water is temporarily pushed down . Derive an expression for its frequency.

    9. Obtain an expression for the time period of a loaded and massless spring (i) Oscillating horizontally (ii) oscillating vertically . Show that is the same as the simple pendulum of length equal to the extension of the spring?

    Numericals-

    1. A body describe S.H.M. with am amplitude of 5cm . and a period of 0.2sec . Find the acceleration and velocity  of the body when the displacement is (a) 5cm (b)3cm (c)0cm.

    2.  Simple pendulum of length l and having a bob of mass m is suspended in a car . The car is moving on a circular path of radius R with a uniform speed v . If the pendulum makes small oscillation in a redial direction about its equilibrium position . What will be its time period?  

    3. A spring balance has a scale that reads from 0 to 50 kg . the length of the scale is 20cm. A body suspended from this balance when displaced and released , oscillation with a period of 0.60 sec. What is the weight of the body?                                            Ans-219N

    4. The acceleration due to gravity on the surface of the moon is 1.7m/s2. What is the time period of the simple pendulum on the moon if its time period on the surface of the earth is 3.5sec?     Ans-8.4 sec

    5. A spring with spring constant 1200N /m is mounted on the horizontal frictionless table , a mass of three kg it attached to the free end of the spring . The mass is then pulled sideway to a distance of 2cm and released . Determine (a) the frequency of oscillation (b)the maximum acceleration of the mass (c) The maximum speed of the mass.          Ans- 3.2 ; 8.1 ; 0.4

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