physics_current_electricity
 Current Electricity Ohm's LawV∝R$V\propto R$V=IR$V=IR$ Drift Velocityvd=-eEm 𝜏${v}_{d}=-\frac{eE}{m}\phantom{\rule{0.22em}{0ex}}𝜏$ where 𝜏$𝜏$=relaxation timeE=electric fieldm=mass of electron Current density=jj=ne2m 𝜏 E$j=\frac{n{e}^{2}}{m}\phantom{\rule{0.22em}{0ex}}𝜏\phantom{\rule{0.22em}{0ex}}E$ Resistance=R=𝜌lA$=R=𝜌\frac{l}{A}$ where, 𝜌=$𝜌=$Resistivity of material Conductivity=𝜎=1𝜌$=𝜎=\frac{1}{𝜌}$ Mobility (𝜇)$\left(𝜇\right)$ is defined as magnitude of the drift velocity per unit electric field.𝜇=| vd |E$𝜇=\frac{|\phantom{\rule{0.22em}{0ex}}{v}_{d}\phantom{\rule{0.22em}{0ex}}|}{E}$ Ammeter: The resistance of Ammeter must be very small compared to other resistances in the circuit. A galvanometer can be converted into Ammeter by connecting a resistor of very low resistance R in parallel. Voltmeter: A galvanometer can be converted into voltmeter by connecting a resistor of high resistance R in series.
 QWhat is Specific resistance ASpecific resistance of a conductor is defined as the resistance offered by conductor per unit length and unit cross-sectional area when the known amount of voltage is applied.Specific Resistance=𝜌=RAL$=𝜌=\frac{RA}{L}$ where,𝜌=$𝜌=$Resistivity of materialR: resistanceA: cross-sectional areaL: length of the material QWhich conservation principle is involved in Kirchoff’s second law?AKirchhoff’s second law or voltage law is a consequence of the law of conservation of energy.