Topic: Electronics Engineering
If a material contains $10^{20}$ molecules/m³, each molecule having a moment of $8.854\times10^{-27}$ C-m parallel to an electric field of $10^{5}V/m.$ then its dielectric constant is
- A. 2.2
- B. 2
- C. 4
- D. 12
Answer: B. 2
Explanation: Average dipole moment $= NP = \epsilon_{0}(\epsilon_{r}-1)E$
Where, $N =$ number of molecules, $P =$ dipole moment
$(\epsilon_{r}-1)=\frac{NP}{\epsilon_{0}E} = \frac{10^{20}\times8.854\times10^{-27}}{10^{5}\times8.854\times10^{-12}}=1$
$\epsilon_{r}=1+1=2$