Basic Electrical Formulas

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This table shows basic electrical formulas used to find voltage, current, resistance, power, and energy, helping analyse and design electrical circuits.

V=\frac WQV= 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 1RG= 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 

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