Physics

Electrostatic Potential and Capacitance

Dielectrics and Polarisation

A molecule of a substance has a permanent electric dipole mome

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Hard

Solving time: 4 mins

A molecule of a substance has a permanent electric dipole moment of magnitude $1 0^{- 29} C$ m. A mole of this substance is polarised (at low temperature) by applying a strong electrostatic field of magnitude $1 0^{6} Vm^{- 1}$ . The direction of the field is suddenly changed by an angle of $6 0^{\circ}$ . 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.

Name: Video answer for A molecule of a substance has a permanent electric dipole moment of magnitude 10−29C m. A mole of this substance is polarised (at low temperature) by applying a strong electrostatic field of magnitude 106Vm−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.
Uploaded: 2023-01-13T07:49:07.000Z
Duration: 19 min

Views: 5,818 students

Updated on: Jan 13, 2023

Text solutionVerified

Here, dipole moment of each molecules

= 1 0^{- 29} C m

As 1 mole of the substance contains

6 \times 1 0^{23}

molecules, total dipole moment of all the molecules,

p = 6 \times 1 0^{23} \times 1 0^{- 29} C m = 6 \times 1 0^{- 29} C m

Initial potential energy,

U_{i} = - pE cos θ = - 6 \times 1 0^{- 6} \times 1 0^{6} cos 0^{\circ} = - 6 J

Final potential energy (when

θ = 6 0^{\circ}

U_{f} = - 6 \times 1 0^{- 6} \times 1 0^{6} cos 6 0^{\circ} = - 3 J

Change in potential energy

= - 3 J - (- 6 J) = 3 J

So, there is loss in potential energy. This must be the energy released by the substance in the form of heat in aligning its dipoles.

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A molecule of a substance has a permanent electric dipole moment of magnitude

1 0^{- 29} C

m. A mole of this substance is polarised (at low temperature) by applying a strong electrostatic field of magnitude

1 0^{6} Vm^{- 1}

. The direction of the field is suddenly changed by an angle of

6 0^{\circ}

. 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.

10 mins ago

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Question Text	A molecule of a substance has a permanent electric dipole moment of magnitude $1 0^{- 29} C$ m. A mole of this substance is polarised (at low temperature) by applying a strong electrostatic field of magnitude $1 0^{6} Vm^{- 1}$ . The direction of the field is suddenly changed by an angle of $6 0^{\circ}$ . 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.
Updated On	Jan 13, 2023
Topic	Electrostatic Potential and Capacitance
Subject	Physics
Class	Class 12
Answer Type	Text solution:1 Video solution: 1
Upvotes	121
Avg. Video Duration	19 min

Text solutionVerified

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