Relative permittivity and permeability of a material are $\varepsilon_{\mathrm{r}}$ and $\mu_{\mathrm{r}}$, respectively. Which of the following values of these quantities are allowed for a diamagnetic material?

(B) $\varepsilon_{\mathrm{r}}=1.5, \mu_{\mathrm{r}}=0.5$

(A) $\varepsilon_{\mathrm{r}}=0.5, \mu_{\mathrm{r}}=1.5$

(C) $\varepsilon_{\mathrm{r}}=0.5, \mu_{\mathrm{r}}=0.5$

(D) $\varepsilon_{\mathrm{r}}=1.5, \mu_{\mathrm{r}}=1.5$

JEE Main · 2008 · 27 Apr 2008 · Offline · Magnetic Properties of Matter

Relative permittivity and permeability of a material are

ε_{r}

and

μ_{r}

, respectively. Which of the following values of these quantities are allowed for a diamagnetic material?

Answer: (B)

A diamagnetic material is very slightly repelled by a magnetic field, which means its relative permeability is a little below one,

μ_{r} < 1

. The relative permittivity, on the other hand, is at least one for any material, since a dielectric only increases the stored electric energy, so

ε_{r} \geq 1

. The only pairing that respects both requirements is

ε_{r} = 1.5

together with

μ_{r} = 0.5

JEE Main · 2008 · 27 Apr 2008 · Offline · Single correct option