This table shows basic electrical formulas used to find voltage, current, resistance, power, and energy, helping analyse and design electrical circuits.
| \(V=\frac WQ\) | V= Electric Potential, Q= Charge, W= Electric potential energy |
| \(I=\frac qt =\frac {n e}{t}\) | I = Current, q = Charge, t = time, n = number of electrons, \(e = -1.6\times10^{-19}\) |
| \( I= n eAv_d \) | n = number of electrons per unit volume, \(e = -1.6\times10^{-19}\), A= area of cross-section of the wire, \(v_d\)= drift velocity of free electrons |
| \(R=\rho \frac lA\) | R= Resistance, \(\rho\) =Resistivity or specific resistance, l= length, A= cross-section area |
| \(G=\frac 1R\) | G= Conductance, R= Resistance |
| \(R_1= R_0(1+\alpha_0t_1) \) | A metallic conductor having resistance \( R_0\) at \(0^{o}C\) and \(R_1 \) at \(t_{1}^{o}C, \alpha _{0}= \) Temperature coefficient of resistance at \(0^{o}C\) |
| \(\alpha _{1} = \frac{\alpha _{0}}{1+\alpha _{0}t_{1}}\) | \(\alpha _{1}\) = Temperature coefficient of resistance at \(t_{1}^{o}C\) \(\alpha _{0} \)= Temperature coefficient of resistance at \(0^{o}C\) |
| \(R_2= R_1[1+\alpha _{1}(t_{2}-t_{1})]\) | Conductor having resistance \(R_2\) at \(t_{2}^{o}C\) and \(R_1\) at \(t_{1}^{o}C\) , \(\alpha _{1}\) = Temperature coefficient of resistance at \(t_{1}^{o}C\) |
| \(V= IR\) | V= Potential Difference, I= Current, R= Resistance |
| \(P= VI=I^{2}R=\frac{V^{2}}{R}\) | P= Electric Power, V= Potential Difference, I= Current, R= Resistance |
| \(W=Pt= VIt=I^{2}Rt=\frac{V^{2}t}{R}\) | W= Electrical energy consumed, P= Electric Power, t= energy consumed time, V= Potential Difference, I= Current, R= Resistance |