CG PET Dielectrics and Polarization — practice questions

Explore 2 free Dielectrics and Polarization questions in CG PET Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Dielectrics and Polarization questions and exercises with answers

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Which of the following molecules is **non-polar** (has zero permanent dipole moment)?Read the answer and worked solution →For a linear isotropic dielectric, the polarization $\vec P$ produced by an applied field $\vec E$ is:Read the answer and worked solution →

Worked practice questions

Which of the following molecules is non-polar (has zero permanent dipole moment)?

H₂O
NH₃
HCl
CO₂

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Correct answer: D. CO₂

CO₂ is linear (O=C=O) the two C=O bond dipoles cancel by symmetry, so net $\vec p = 0$. HCl, H₂O (bent, ~105°) and NH₃ are polar with permanent dipole moments and behave as polar dielectrics.

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For a linear isotropic dielectric, the polarization $\vec P$ produced by an applied field $\vec E$ is:

$\vec P = \chi_e \vec E^2$
$\vec P = \chi_e^2 \vec E$
$\vec P = \chi_e \vec E$
$\vec P = \vec E / \chi_e$

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Correct answer: C. $\vec P = \chi_e \vec E$

The induced dipole moment per unit volume is proportional to the applied field for linear isotropic media: $\vec P = \chi_e \vec E$, where $\chi_e$ is the electric susceptibility. For vacuum $\chi_e = 0$.