A molecule with a dipole moment p is placed in an electric field of strength E. Initially the dipole is aligned parallel to the field. If the dipole is to be rotated antiparallel to the field, the work required to be done by an external agency is

Question

A molecule with a dipole moment p is placed in an electric field of strength E. Initially the dipole is aligned parallel to the field. If the dipole is to be rotated antiparallel to the field, the work required to be done by an external agency is (A) -2 p E (B) -p E (C) p E (D) 2 p E

Tardigrade Admin · Accepted Answer

W=p E(1- cos θ) here θ=180° ∴ W=p E(1- cos 180°) =p E[1-(-1)]=2 p E

Q. A molecule with a dipole moment $p$ is placed in an electric field of strength $E$ . Initially the dipole is aligned parallel to the field. If the dipole is to be rotated antiparallel to the field, the work required to be done by an external agency is

-2 p E

-p E

p E

2 p E

$W = pE (1 - cos θ)$ here $θ = 18 0^{\circ}$
$∴ W = pE (1 - cos 18 0^{\circ})$
$= pE [1 - (- 1)] = 2 pE$

Q. A molecule with a dipole moment p is placed in an electric field of strength E. Initially the dipole is aligned parallel to the field. If the dipole is to be rotated antiparallel to the field, the work required to be done by an external agency is

-2 p E

-p E

p E

2 p E

W=pE(1−cosθ) here θ=180∘ ∴W=pE(1−cos180∘) =pE[1−(−1)]=2pE

Q. A molecule with a dipole moment $p$ is placed in an electric field of strength $E$ . Initially the dipole is aligned parallel to the field. If the dipole is to be rotated antiparallel to the field, the work required to be done by an external agency is

$W = pE (1 - cos θ)$ here $θ = 18 0^{\circ}$
$∴ W = pE (1 - cos 18 0^{\circ})$
$= pE [1 - (- 1)] = 2 pE$