Home
Class 12
PHYSICS
A molecule of a substance has permanent ...

A molecule of a substance has permanent dipole moment p. A mole of this substance is polarised by applying a strong electrostatic field E. The direction of the field is suddenly changed by an angle of `60^(@)`. If N is the Avogadro's nwnber the amount of work done by the field is ......

A

2 NpE

B

`(1)/(2) ` NpE

C

NpE

D

`(3)/(2) ` Npe

Text Solution

Verified by Experts

The correct Answer is:
A, B
For 1 mole : W = pE(1- cos `theta`)
For N mole : W = N p E ( 1- cos `theta`)
`:. W = Np E 9 1 - cos 60^(@)]`
` :. W = NpE [ 1 -(1)/(2)]`
`:. W = NpExx(1)/(2)`
`:. W = (1)/(2) ` N pE
Promotional Banner

Topper's Solved these Questions

  • ELECTROSTATIC POTENTIAL AND CAPACITANCE

    KUMAR PRAKASHAN|Exercise Section D ( Multiple Choice Questions (MCQs) )|93 Videos

  • ELECTROMAGNETIC WAVES

    KUMAR PRAKASHAN|Exercise BOARD.S QUESTION PAPER MARCH - 2020 (PART - B) SECTION - C|5 Videos

  • MAGNETISM AND MATTER

    KUMAR PRAKASHAN|Exercise SECTION D Multiple Choice Questions (MCQs) (MCQs asked in Competitive Exams) MCQs asked in Board Exam and GUJCET|7 Videos

Similar Questions

Explore conceptually related problems

A molecule of a substance has a permanent electric dipole moment of magnitude 10^(-30) Cm. A mole of this substance is polarised (at low temperature) by applying a strong electrostatic field of magnitude 10^(7) vm^(-1) . The direction of the field is suddenly changed by an angle of 60^(@) . Estimate the heat released by the substance in aligning its dipole along the new direction of the field. For simplicity assume 100 % polarisation of the sample. 1 mole = 6 xx 10^(23) molecule.

A molecule of a substance has a permanent electric dipole moment of magnitude 10^(-29) C m. A mole of this substance is polarised (at low temperature) by applying a strong electrostatic field of magnitude 10^(6) V m^(-1) . The direction of the field is suddenly changed by an angle of 60^(@) . Estimate the heat released by the substance in aligning its dipoles along the new direction of the field. For simplicity, assume 100% polarisation of the sample.

An electric dipole of moment p is placed parallel to the lines of force of electric field E, then the work done in deflecting it through an angle of 180 degree is

The work in rotating electric dipole of dipole moment p in an electric field E through an angle theta from the direction of electric field, is:

An electric dipole of moment p is placed normal to the lines of force of electric field E, then the work done in deflecting it through an angle of 180 degree is

An electric dipole of dipole moment vecP is placed parallel to the uniform electric field of intensity vecE. On rotating it through 180^(@) the amount of work done is ..... .

Answer carefully: (a) Two large conducting spheres carrying charges Q_(1) and Q_(2) are brought close to each other. Is the magnitude of electrostatic force between them exactly given by Q_(1),Q_(2)//4pi epsilon_(0)r^(2) , where r is the distance between their centres? (b) If Coulomb’s law involved 1//r^(3) dependence (instead of would Gauss’s law be still true ? (c) A small test charge is released at rest at a point in an electrostatic field configuration. Will it travel along the field line passing through that point? (d) What is the work done by the field of a nucleus in a complete circular orbit of the electron? What if the orbit is elliptical? (e) We know that electric field is discontinuous across the surface of a charged conductor. Is electric potential also discontinuous there? (f) What meaning would you give to the capacitance of a single conductor? (g) Guess a possible reason why water has a much greater dielectric constant (= 80) than say, mica (= 6).

A non-uniform electric field is represented by vecE = 5xhati Vm^(-1) . An electric dipole having moment. P = 20 xx 10^(-20) cm is placed at an angle of 60° with the field. The net force on the dipole is.........N.

(a) Show that the normal component of electrostatic field has a discontinuity from one side of a charged surface to another given by (E_(2)-E_(1)).n = sigma/epsilon_(0) where hatn is a unit vector normal to the surface at a point and sigma is the surface charge density at that point. (The direction of hatn is from side 1 to side 2.) Hence, show that just outside a conductor, the electric field is sigma hatn //epsilon_(0) . (b) Show that the tangential component of electrostatic field is continuous from one side of a charged surface to another. [Hint: For (a), use Gauss’s law. For, (b) use the fact that work done by electrostatic field on a closed loop is zero.]

KUMAR PRAKASHAN-ELECTROSTATIC POTENTIAL AND CAPACITANCE-Section D ( MCQs asked in Cometitive Exams )
  1. A capacitor of 2 muF is charged as shown in the diagram . When the swi...

    Text Solution

    |

  2. A parallel-plate capacitor of area A, plate separation d and capacitan...

    Text Solution

    |

  3. A molecule of a substance has permanent dipole moment p. A mole of thi...

    Text Solution

    |

  4. A parallel plate capacitor is to be designed using a dielectric of die...

    Text Solution

    |

  5. A wheel having mass m has charges + q and - q on diametrically opposit...

    Text Solution

    |

  6. Q amount of electric charge is present on the surface of a sphere hav...

    Text Solution

    |

  7. Charges 1 mu c are placed at each of the four corners of a square of s...

    Text Solution

    |

  8. Energy of a charged capacitor is U. Now it is. removed from the batter...

    Text Solution

    |

  9. The dimensional formula of capacitance ls ...... Take Q as the dimensi...

    Text Solution

    |

  10. A uniform electric field is prevailing in X- direction in certain regi...

    Text Solution

    |

  11. An electric dipole of dipole moment vecP is placed parallel to the uni...

    Text Solution

    |

  12. Ten identical square metallic plates are arranged as shown in figure. ...

    Text Solution

    |

  13. On the axis and on the equator of an electric dipole for all points .....

    Text Solution

    |

  14. The unit of polarizabity of the molecule is .........

    Text Solution

    |

  15. The unit of Intensity of polarization is ........

    Text Solution

    |

  16. In the figure area of each plate is A and the distance between consecu...

    Text Solution

    |

  17. A moving positive charge approaches a negative charge. What will happe...

    Text Solution

    |

  18. Value of dielectric strength for air is ...... Vm^(-1)

    Text Solution

    |

  19. Three capacitors of 2 pF, 3 pF and 4 pF are connected in parallel. Wha...

    Text Solution

    |

  20. Equipotential surface through a point is ...... to the electric field ...

    Text Solution

    |