Physics Classes

Category: 12th Assignments

  • Complete assignment of electrostatics

    Complete assignment of electrostatics

    Complete assignment of electrostatics

    Students as you know , physics classes by Nayan jha already provided many kind of assignment of the chapter Electrostatics . But this is the Complete assignment of electrostatics . It contains objective type,fill in the blanks,1 marks,2 marks,3 marks and 5 marks questions with numerical and HOTS .

    Previously assignment of electrostatics , Objective questions of electrostatics , Important questions of electrostatics and numericals of electrostatics is already provided .In the previous assignment electric charges and field and electrostatics potential and capacitance are in different -different assignment . But here we are providing all kind of questions of both the chapters in one assignment .

    By clicking here students can see the complete syllabus of class 12th physics (CBSE) .

    It will help the students to revise complete chapter .which will help the students preparing for 12th board and all kind of competitive  examinations .

    Before to solve the questions of these assignment student must learn complete notes of these two chapters , electric charges and field and electrostatic potential and capacitance .

    To get the notes of  both the chapters of electrostatics click here-

    After revise the entire chapters of electric charges and field and electrostatic potential and electrostatics.Students may solve the questions of related chapters. Here is the Complete assignment of electrostatics  –

     To download the complete assignment Electric charges and field click here-

    To download the complete assignment Electrostatic potential and capacitors click here-

     

  • Energy stored in a capacitor and energy density

    Energy stored in a capacitor and energy density

    Energy stored in a capacitor and energy density .

    Before to know about the Energy stored in a capacitor and energy density , student must have to know about capacitors . To know about the capacitor click here–

    In this topic we will discuss about the Energy stored in a capacitor and energy density, when a capacitor is charged from zero to Q .

    ENERGY STORED IN A CAPACITOR –

    Suppose the plates of the capacitor is initially uncharged , and the charge is to be transferred from plate 2 to plate 1 , at a small time charge dQ transferred and at the final time it reaches from 0 to Q .   

     

    Let V is the potential difference across the plates then work done for small instant is

    dW = V . dQ  = (Q/C)dQ .

    integrating both sides,

    ∫ dW =∫(Q/C)dQ from limit 0 to Q ,  then we get ,

    net work done W = Q2/2C ,

    also as we know Q=CV,  so work done may be written as ,

    W = potential energy stored = U =( ½) CV2   = ½ QV .

    If we plot the graph  potential v/s charge we get,

     

    ***Similarly we can plot the graph (i)  U v/s V ( when C is constant )

    (ii) U v/s C (when V is constant)

    (iii) U v/s V  (when Q is constant)

    Total energy stored in the combination of capacitors –

    In  series combination –  U = Q2/2CS But in series combination 1/Cs = 1/C1  + 1/C2 + 1/C3   ….

    So we can write in series combination total energy U = U1 + U2 + U3 + …..

    In parallel combination – U = ½ Cp V2 = ½ C1 V2 + ½ C2 V2 + ½ C3V2 …..

    So we can write in parallel combination total energy of the combination   U = U1+ U2 + U3 ……

    Energy density of a  parallel plate capacitor –

    Energy density of the capacitor is the energy stored per unit volume of the capacitors or condensers . We can write energy density u = U/ ( volume )

    u = ( ½ C V2 )/ A d  ( Where A is the area of the plate and D is the separation between the plates .

    But potential V = E( electric field) d  . putting this value in the above equation we get  ,

    u = ½ ( ϵ0 A /d ) ( E2 d2 / Ad ) = ½ ϵ0 E2 .

    the  unit of energy density is  J/m3 .

     

     

  • Numerical based on electric charge ,electric field .

    Numerical based on electric charge ,electric field .

    Numerical based on electric charge ,electric field .

    Numerical based on electric dipole ( electric field at axial and equatorial point, torque and potential energy stored in dipole )-

    1. Two charges + 30μc and -30μc are placed 1cm apart . calculate electric field at a point on the the axial and equatorial line at a distance of 20 cm from the centre of the dipole .

    Ans- 6.25 x 105 N/C and 3,25 x 105‑ N/C .

    1. An electric dipole of dipole moment 4 x 10-5 C-m is placed in uniform electric field of 103 N/C making an angle of 300 with the direction of field . Determine the torque exerted by the electric field on the dipole.    Ans- 2 x 10-8Nm .
    2. An electric dipole is placed at an angle of 600 with an electric field of magnitude 4 x 105 N /C . It experience a torque of 8√3 Nm . If the length of the dipole is 2cm , determine the magnitude of either charge of the dipole . Ans –  2 x 10-3 C .
    3. An electric dipole of length 10cm having charges of magnitude 6 x 10-3 C , placed at 300 with respect to a uniform electric field experience a torque of magnitude 6√3 N-m . Calculate (i) magnitude of the field and (ii) potential energy of the dipole . Ans- 2√3x 104; -18J
    4. An electric dipole consist of two opposite charges of magnitude q=1×10-6C separated by 2.0 cm . The dipole is placed in an external electric field of 1×105 N/C . What maximum torque does the field exert on the dipole ? How much work must an external agent to do turn the dipole end for end , starting from position of alignment ( ϴ=00 ) . Ans- 2×10-3 N-m ; 4×10-3J .
    5. (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 .

    7.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.

    8.The sum of two point charges is 7µc they repel each other with a force of 1N when kept 30 cm apart in free space , calculate the value of each charge.

    To download the complete assignment (pdf) based on numerical based on electric charge electric field click here-

     

  • Numerical based on electric field

    Numerical based on electric field

    Numerical based on electric field

    This topic contain numerical for the practice of the chapter electric field

    Before to solve the numerical based on electric field students has to study ( learn ) , and all the notes based on electric field , electric dipole ( axial and equatorial point)

    To read or download the notes on electric field click here-

    To read or download the notes on electric dipole , electric field at equatorial and axial point click here-

    Numerical based on electric field

    1. Two point charges +16μc and -9μc are placed 8cm apart in air . Determine the position of the point at which the resultant electric field is zero .          [ Ans-  24 cm]
    2. A particle of mass m and charge q is thrown at speed u against a uniform electric field E . How much distance will it travel before coming to momentary rest . ?   [Ans- mu2/2qE]
    3. A particle of mass m and charge q is released from rest in uniform electric field of intensity E . Calculate the kinetic energy it attains after moving a distance a distance x between the plates .   [Ans- qEx]
    4. Eight identical point charges of q coulomb each are placed at the corners of a cube of each side 0.1 m . calculate the electric field at the centre of the cube . calculate the field at the centre when one of the corner charge is removed .   [Ans – 0 ; 1.2 x 1012 .]
    5. Two charges + 30μc and -30μc are placed 1cm apart . calculate electric field at a point on the the axial and equatorial line at a distance of 20 cm from the centre of the dipole .                        [ Ans- 6.25 x 105 N/C and 3,25 x 105‑ N/C .]
    6. Four particles each of charge q are be placed on the vertices A ,B, C, D of a regular pentagon ABCDE . the distance of each corner from the centre is ‘a’ . Calculate the electric field at the centre of the pentagon .   [ Ans- q/4∏ϵ0 a2 along OE .]
    7. A small sphere of mass 1g carries a charge of +6μc . The sphere is suspended by a string in an electric field of 400N/C acting downwards. Calculate the tension in the string . What will be the tension if the charge on the sphere be -6μc .                                       [Ans- 1.22x 10-2 N . ; 74 x 10-4 N .]
    8. An electron falls through a distance of 1.5 cm in uniform electric field of value 2 x104N/C . when the direction of electric field is reversed , a proton falls through the same distance . compare the time of fall in each case .
    9. A particle of mass ‘m’ and charge -q enters the region between two charged plates initially moving along x-axis with speed vx ( as shown in the fig) . The length of the plate is L and an uniform electric field E is maintained between the plates . Show that the vertical deflection of the particle at the far edge of the plate is    QelL2 / (2m vx2) .                                                                                           
    10. As shown in the figure three charged particles in a uniform electrostatic field . Give the sign of three charges . Which particle has the highest charge to mass ratio .                                                             

     

  • Objective questions of ray optics

    Objective questions of ray optics

    Objective questions of ray optics

    this assignment will provide the important Objective questions of ray optics for  students preparing for class-12th board examination and for the students preparing for JEE/NEET and other competitive examinations.

    Reflection and Refraction of Light at Plane Surface ( Objective questions of ray optics)

    1. When light travels from glass to air, the incident angle is and the refraction angle is .the true relation is :(a)θ 1 =θ 2      (b)  θ 1 >θ2  (c)θ1 <θ2  (d)Not predictable
    2. Two mirrors are kept at 60 to each other and a body is placed in the middle.The total number of images formed is:(a)Three(b)Four (c)Five (d)Six
    3. If an object is placed unsymmetrically between two plane mirrors inclined at an angle 72 ,then the total number of images formed is:(a)5   (b)4    (c)2   (d)infinite
    4. If an object is placed symmetrically between two plane mirrors, inclined at an angle of 72 .than the total total number of images formed is:(a)5 (b)4 (c)2 (d)Infinite

    5) A ray of light is incident on a plane mirror at an angle of incidence of 30⁰ ,the deviation

    Produced by the mirror is :

    (a) 30 ⁰ ( b) 60⁰

    (c) 90⁰ (d) 120

    6) when a ray of light enters a glass slab from air:

    (a) its wavelength decreases

    (b) its wavelength decreases

    (c) its frequency increases

    (d) neither wavelength nor frequency changes

    7) When a light enters from air to water, then its:

    (a) frequency increases and speed decreases

    (b) frequency is the same but the wavelength is smaller in water then in air:

    (c) frequency is same but wavelength in water is greater than in air

    To download complete assignment of ray optics click here-objective ray optics

  • Objective questions of capacitance

    Objective questions of capacitance

    Objective questions of capacitance

    This assignment contains all important  objective questions of capacitance, it will be beneficial for the students preparing for class 12th board examination or preparing for JEE/NEET.

    Before to solve this assignment student must solve the assignment of its previous chapter electric field and potential, to download the assignment of objective questions of electric field and potential click here.

    Capacitance

    1. There are 27 drops of a conducting fluid. Each has a radius r and they are charged to a potential V0. These are combined to from a bigger drop. Its potential will be:
    • (a)V0      (b) 3V0    (c) 9V0          (d) 27V0
    1. 1000 small water drops each of radius r and charge q coalesce together to from one spherical drop. The potential of the bigger drop is larger than that of the smaller one by a factor:
    • (a)1000        (b) 100         (c) 10          (d) 1
    1. The capacitance of a parallel plate condenser does not depend upon:
    • (a)area of the plates
    • (b)medium between the plates
    • (c)distance between the plates
    • (d)metal of the plates
    1. The force between the plates of a parallel plate capacitor of capacitance C and distance of separation of the plates d with a potential difference V between the plates is:
    • (a)CV2/2d (b) C2V2/2d2    (c) C2V2/d2      (d) V2d/C
    1. A parallel plate capacitor is made by stacking n equally spaced plates connected alternately. If the capacitance between any two plates is C, then the resulting capacitance is:
    • (a)C    (b) nC         (c) (n-1)C        (d) (n+1)C
    1. Two parallel metal plates carry charge +Q and -Q respectively. A test charge q0 placed between them experiences a force F. Now the separation between the plates is doubled, then the force on the test charge will be:
    • (a)F         (b) 2F             (c) F/2              (d) F/4
    1. A 2μF capacitor is charged to a potential of 200 V and then isolated. When it is connected in parallel with a second capacitor which is uncharged, the common potential becomes 40 V. The capacitance of the second capacitor is:
    • (a)2μF        (b) 4μF        (c) 8μF       (d) none of these
    1. Three capacitors of capacitance 12μF each are available. The minimum and maximum capacitance which may be obtained from these are:
    • (a)12μF, 36μF (b) 4μF, 12μF    (c) 4μF, 36μF   (d) 0μF, ꚙμF

    To download entire assignment of objective questions of electric field click here -objective questions of Capacitance

     

    To solve the assignment of important objective  questions of electric current click here.

    electric- current
    electric- current

     

  • Objective questions of alternating current

    Objective questions of alternating current

    Objective questions of alternating current

    LC-OSCILLATOR

    This assignment (Objective questions of alternating current),provide the important objective questions of the chapter alternating current ,which is important for the students preparing for class-12th board examination or , other competitive examinations (JEE/NEET)

    Before to solve this assignment (Objective questions of alternating current), student should solve the assignment of objective questions of electromagnetic induction-

    1. A direct current of 5 amp is superimposed on an alternating current I = 10sin ɷt flowing through a wire. The effective value of the resulting current will be:
    • (a)(15/2) amp     (b) 5√3 amp  (c) 5√5 amp      (d) 15 amp
    1. In an AC circuit, a resistance of R ohm is connected in series with an inductance L. If phase angle between voltage and current is 45°, the value of inductive reactance will be:
    • (a)R/4
    • (b)R/2
    • (c)R
    • (d)cannot be found with the given data
    1. Resonance frequency of L – C circuit is:
    • (a)1/2π √LC       (b) 1/2πLC   (c) 1/2π √L/C   (d) 1/2π √LC
    1. In L-C-R series AC circuit, the phase angle between current and voltage is:
    • (a)any angle between 0 and ± π/2
    • (b)π/2
    • (c)π
    • (d)any angle between 0 and π
    1. In an L-C-R circuit, the capacitance is made one-fourth, when in resonance, so that the circuit remains in resonance?
    • (a)4 times    (b) (1/4) times       (c) 8 times        (d) 2 times

    TO download complete assignment of Objective questions of alternating Current- click here-

  • Objective questions of electromagnetic induction

    Objective questions of electromagnetic induction

    Objective questions of electromagnetic induction-

    This assignment contains Objective questions of electromagnetic induction, which will help the students to prepare for class 12th board examination and other competitive exams like JEE/NEET.

    Before to solve this assignment students has to solve assignment of magnetic effect of current, to solve the questions of magnetic effect of current click here

    1. Lenz’s law is a consequence of the law of conservation of:
    • (a)charge      (b) mass     (c) momentum      (d) energy
    1. The law of electromagnetic induction have been used in the construction of a:
    • (a)galvanometer (b) voltmeter    (c) electric motor   (d) generator
    1. A cylindrical bar magnet is kept along the axis of a circular coil. On rotating the magnet about the axis, the coil will have induced in it:
    • (a)a current (b) no current       (c) only an em        (d) both an emf and a current
    1. A horizontal straight conductor when placed along south-north direction falls under gravity; there is:
    • (a)an induced current from south to north direction
    • (b)an induced current from north to south direction
    • (c)no induced emf along the length of the conductor
    • (d)an induced emf along the length of the conductor
    1. A car moves on a plane road. Induced emf produced across the axle is maximum when it moves:
    • (a)at the poles (b)moves at equator (c) remains stationary
    • (d) no emf is induced at all

    To download complete assignment of objective questions of electromagnetic induction click here-Electromagnetic Induction

    after solving this assignment of objective questions of electromagnetic induction student should solve the assignment of objective questions of alternating current . To download the complete assignment of objective questions of alternating current click here –

  • Objective questions of magnetism and matter

    Objective questions of magnetism and matter

    Objective questions of magnetism and matter

    This assignment contains all type objective questions of magnetism and matter. it will be helpful for the students preparing for class 12th board examination or other competitive examinations like JEE/ NEET .

    Magnetism and matter

    1. With the tangent galvanometer it is desirable to have a deflection near 45°; then the percentage error:
    • (a)is less in the reading of deflection
    • (b)is negligible in the reading of deflection
    • (c)is less in the measurement of current
    • (d)is large in the measurement of current
    1. The sensitivity of a moving coil galvanometer depends on:
    • (a)the angle of deflection
    • (b)the earth’s magnetic field
    • (c)torsional constant of the spring
    • (d)the moment of inertia of the coil
    1. An ammeter can be converted into a voltmeter by connecting:
    • (a)a high resistance in series
    • (b)a low resistance in parallel
    • (c)a low resistance in series
    • (d)a high resistance in parallel
    1. In a moving coil galvanometer the deflection of the coil θ is related to the electric current I by the relation:
    • (a)I ꭀ tan θ       (b) I ꭀ θ                   (c) I ꭀ θ2                      (d) I ꭀ √θ
    1. A voltmeter of range 2V and resistance 300 Ω cannot be converted into ammeter of range:
    • (a)1 A      (b) 1 mA             (c) 100 mA              (d) 10 mA
    1. The effect due to uniform magnetic field on a freely suspended magnetic needle is as follows:
    • (a)both torque and net force are present
    • (b)torque is present but no net force
    • (c)both torque and net force are absent
    • (d)net force is present but not torque
    1. A voltmeter has a resistance of G ohm and range V volt. The value of resistance used in series to convert it into voltmeter of range nV volt is:
    • (a)nG       (b) (n – 1)G               (c) G/n                   (d) G/(n – 1)
    1. An ammeter has a resistance of G ohm and a range of I The value of resistance used in parallel to convert it into an ammeter of range nI amp is:
    • (a)nG       (b) (n – 1)G               (c) G/n               (d) G/(n – 1)
    1. To reduce the range of a voltmeter, its resistance need to be reduced. Which of the following resistance when connected in parallel will convert it into a voltmeter of range (V/n)?
    • (a)nR0 (b) (n + 1)R0     (c) (n – 1)R0        (d) None of these

    To download entire  assignment click here- Magnetism and matter objective

     

     

  • Objective questions of magnetic effect of current

    Objective questions of magnetic effect of current

    Objective questions of magnetic effect of current

    this assignment contains all important objective type  questions of  magnetic effect of current . Students preparing for 12th board examination or other competitive examination  like JEE/NEET.

    Before to solve objective questions of this chapter student may solve the objective questions of electric current. To download assignment of objective questions of electric current click here- 

    1. Magnetic induction is measured in:
    •  (a)weber (b) weber/m     (c) weber/m2      (d) weber/m3
    1. The force acting on a charge q moving with a velocity ʋ in a magnetic field of induction B is given by:
    • (a) q/(ʋ ₓ B) (b) (ʋ ₓ B)/q      (c) q/(ʋ ₓ B)         (d) (ʋ . B)q
    1. Two free parallel wire carrying currents in the opposite directions:
    • (a)attract each other
    • (b)repel each other
    • (c)do not affect each other
    • (d)get rotated to be perpendicular to each other
    1. Two parallel wires carrying currents in the same direction attract each other because of:
    • (a)potential difference between them
    • (b)mutual inductance between them
    • (c)electric forces between them
    • (d)magnetic force between them
    1. A free charged particle moves through a magnetic field. The particle may undergo a change in:
    • (a)speed  (b)energy   (c) direction of motion  (d) none these
    1. An electron and a proton travel with equal speeds and in the same direction, at 90° to a uniform magnetic field. They experience forces which are initially: