Part I - Electric & Magnetic Field In Material Space - Questions With Answers (Short Notes)
1. What Do You Mean By Dielectric Constant Of A Material ? Answer: Dielectric constant (k) or relative permittivity (ε r ) is defined as the ratio of capacitance of a capacitor with dielectric to the capacitance of same capacitor without dielectric. It generally describes the ability of a material to polarize and store a charge. Mathematically, k or ε r = C/C 0 . [Since C = q/V, we have ε r = E 0 /E = V 0 /V = ε/ε r ]. 2. Define Dielectric Medium. Answer: Dielectric is a material in which energy can be stored by the polarization of the molecules. It is a material that increases the capacitance or charge storage ability of a capacitor. Ideally, a dielectric is an insulator and does not contain free charge. However, in the presence of external field it exhibits a relative displacement of opposite bound charges and hence the polarization of the medium. Due to polarization induced surface charges tend to weaken the original field within the dielectric. [The resultan...