# Relative permittivity and permeability of a material are $\varepsilon _{r}\; and \; \mu _{r}$ ,  respectively. Which of the following values of these quantities are allowed for a diamagnetic mateiral? Option 1) $\varepsilon _{r}=1.5,\; \mu _{r}=1.5$ Option 2) $\varepsilon _{r}=0.5,\; \mu _{r}=1.5$ Option 3) $\varepsilon _{r}=1.5,\; \mu _{r}=0.5$ Option 4) $\varepsilon _{r}=0.5,\; \mu _{r}=0.5$

P Prateek Shrivastava

As we learnt in

Relative Permeability -

$\mu _{r}=\frac{\mu }{\mu _{0}}$

- wherein

$\mu$ - relative permeability of any medium

$\mu_0$ - relative permeability of air or vaccum

Magnetic Permeability -

$\mu =\mu _{o}\mu _{r}$

- wherein

$\mu _{0}$ - absolute permeability of air

$\mu _r$ - relative permeability

$\mu _{0}=4\pi \times 10^{-7}$ tesla m/amp

The values of relative permeability of diamagnetic materials are slightly less than 1 and $\varepsilon _{r}$ is quite high. According to the table given,

one takes  $\varepsilon _{r}=1.5\: and\; \mu _{r}=0.5.Then \; the\; choice (c) \; is \; correct.$

Option 1)

$\varepsilon _{r}=1.5,\; \mu _{r}=1.5$

Incorrect

Option 2)

$\varepsilon _{r}=0.5,\; \mu _{r}=1.5$

Incorrect

Option 3)

$\varepsilon _{r}=1.5,\; \mu _{r}=0.5$

Correct

Option 4)

$\varepsilon _{r}=0.5,\; \mu _{r}=0.5$

Incorrect

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