cbse class 12 physics important derivations

Important Derivations for Class 12 Physics Chapter 8 Electromagnetic Waves (1) Derive expression for displacement current The electric flux between the plates of a capacitor is given by $$ \begin{aligned} & \phi_{\mathrm{E}}=\mathrm{EA}=\frac{\mathrm{Q}}{\varepsilon_0 \mathrm{~A}} \cdot \mathrm{A}=\frac{\mathrm{Q}}{\varepsilon_0} \\ & \quad \frac{\mathrm{d} \phi_{\mathrm{E}}}{\mathrm{dt}}=\frac{\mathrm{d}}{\mathrm{dt}}\left(\frac{\mathrm{Q}}{\varepsilon_0}\right)=\frac{1}{\varepsilon_0} \frac{\mathrm{dQ}}{\mathrm{dt}} \\ & \quad \frac{\mathrm{d} \phi_{\mathrm{E}}}{\mathrm{dt}}=\frac{1}{\varepsilon_0} \mathrm{i} \quad \quad\left(\text { As, } \mathrm{i}=\frac{\mathrm{dQ}}{\mathrm{dt}}\right) \\ & … Read more