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How does the electric field inside a polarized linear dielectric slab, subjected to an external electric field ($E_0$), compare to the external field?
The text states: 'The field produced by these surface charges opposes the external field. The total field in the dielectric is, thereby, reduced from the case when no dielectric is present.'
The dielectric constant (K) of a substance is defined as the ratio of its permittivity ($\epsilon$) to the permittivity of free space ($\epsilon_0$). Based on the provided context, for any dielectric (K > 1), how does the capacitance (C) of a capacitor with the dielectric relate to its capacitance in vacuum (C$_0$)?
The NCERT provides the relationship: '$C = K C_0$ (2.54)'. It also states: 'Thus, the dielectric constant of a substance is the factor (>1) by which the capacitance increases from its vacuum value, when the dielectric is inserted fully between the plates of a capacitor.'
For polar molecules in the absence of an external electric field, their permanent dipoles are oriented randomly. What causes this random orientation?
The text explains for polar molecules: 'In the absence of any external field, the different permanent dipoles are oriented randomly due to thermal agitation; so the total dipole moment is zero.'
When an external electric field is applied to a dielectric composed of polar molecules, what two factors determine the extent of polarization?
As per the NCERT: 'The extent of polarisation depends on the relative strength of two mutually opposite factors: the dipole potential energy in the external field tending to align the dipoles with the field and thermal energy tending to disrupt the alignment.'
What is the unit of Polarization (P) as listed in the 'Physical quantity Symbol Dimensions Unit Remark' table?
The table explicitly states: 'Polarisation P [L$^{-2}$ AT] C m$^{-2}$ Dipole moment per unit volume'.
A capacitor has its plates separated by a dielectric. The product $\epsilon_0 K$ is referred to as:
The NCERT states: 'The product $\epsilon_0 K$ is called the permittivity of the medium and is denoted by $\epsilon = \epsilon_0 K$ (2.52).'
In the presence of an external electric field, a dielectric material develops surface charges ($\pm \sigma_p$) on its faces normal to the field. How do these induced surface charges affect the total electric field inside the dielectric?
The text states: 'The field produced by these surface charges opposes the external field. The total field in the dielectric is, thereby, reduced from the case when no dielectric is present.'
Why does a volume element ($\Delta v$) within a polarized dielectric slab, far from its surfaces, have no net charge, even though it possesses a net dipole moment?
The NCERT mentions: 'Anywhere inside the dielectric, the volume element $\Delta v$ has no net charge (though it has net dipole moment). This is, because, the positive charge of one dipole sits close to the negative charge of the adjacent dipole.'
Which type of molecule, when polarized by an external field, primarily exhibits an alignment effect of its existing permanent dipoles rather than a significant induced dipole moment effect?
The text states for polar molecules: 'there may be, in addition, the 'induced dipole moment' effect as for non-polar molecules, but generally the alignment effect is more important for polar molecules.'
Which of the following events strictly indicates the onset of a new menstrual cycle?
The menstrual cycle starts with the menstrual phase, when menstrual flow occurs. This flow marks the beginning of a new cycle after the degeneration of the corpus luteum in the absence of fertilization. (Refer to paragraph 1, page 34: 'The cycle starts with the menstrual phase, when menstrual flow occurs...').
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The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.