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Key Equations

Average electrical current Iave=ΔQΔtIave=ΔQΔt
Definition of an ampere 1A=1C/s1A=1C/s
Electrical current I=dQdtI=dQdt
Drift velocity vd=InqAvd=InqA
Current density I=areaJ·dAI=areaJ·dA
Resistivity ρ=EJρ=EJ
Common expression of Ohm’s law V=IRV=IR
Resistivity as a function of temperature ρ=ρ0[1+α(TT0)]ρ=ρ0[1+α(TT0)]
Definition of resistance RVIRVI
Resistance of a cylinder of material R=ρLAR=ρLA
Temperature dependence of resistance R=R0(1+αΔT)R=R0(1+αΔT)
Electric power P=IVP=IV
Power dissipated by a resistor P=I2R=V2RP=I2R=V2R
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