The potential gradient at which the dielectric of a condenser just gets punctured is called

What is a linear isotropic dielectric?

What happens if the magnitude of the capacitance of a capacitor is large? Define dielectric breakdown and dielectric strength.

$A$ cube of side $1 \ cm$ contains $100$ molecules,each having an induced dipole moment of $0.2 \times 10^{-6} \ C \cdot m$ in an external electric field of $4 \ N \cdot C^{-1}$. The electric susceptibility of the material is .... $C^2 \cdot N^{-1} \cdot m^{-2}$.

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: Net dipole moment of a polar dielectric substance is zero in the absence of an external electric field.
Reason $(R)$: In the absence of an external electric field,the different permanent dipoles of a polar dielectric substance are oriented in random directions.
In the light of the above statements,choose the most appropriate answer from the options given below.

When a dielectric is placed in an external electric field,the electric field inside the dielectric is