Electric current: 1 Amp (A) = 1 Coulomb (C) per second (s)
Current= I = d Q / d t = n q v d A {\displaystyle I=dQ/dt=nqv_{d}A} , where
( n , q , v d , A ) {\displaystyle (n,q,v_{d},A)} = (density, charge, speed, Area)
I = ∫ J → ⋅ d A → {\displaystyle I=\int {\vec {J}}\cdot d{\vec {A}}} where J → = n q v → d {\displaystyle {\vec {J}}=nq{\vec {v}}_{d}} =current density.
E → = ρ J → {\displaystyle {\vec {E}}=\rho {\vec {J}}} = electric field where ρ {\displaystyle \rho } = resistivity
ρ = ρ 0 [ 1 + α ( T − T 0 ) ] {\displaystyle \rho =\rho _{0}\left[1+\alpha (T-T_{0})\right]} , and R = R 0 [ 1 + α Δ T ] {\displaystyle R=R_{0}\left[1+\alpha \Delta T\right]} ,
where R = ρ L A {\displaystyle R=\rho {\tfrac {L}{A}}} is resistance
V = I R {\displaystyle V=IR} and Power= P = I V = I 2 R = V 2 / R {\displaystyle P=IV=I^{2}R=V^{2}/R}
, where
= (density, charge, speed, Area)
where 
=current density.
= electric field where 
= resistivity
![{\displaystyle \rho =\rho _{0}\left[1+\alpha (T-T_{0})\right]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/b63fbf7f93624cb84d99cade118b295c49351ffb)
, and ![{\displaystyle R=R_{0}\left[1+\alpha \Delta T\right]}](https://wikimedia.org/api/rest_v1/media/math/render/svg/f43d434660a8941a886bce1f85d9d027d30d6303)
,
is resistance
and Power=
