ElectrodynamicsCreated by:

Gita Ravhani Anugrah (409322017)

State University of Medan

Material

A.Electric Current

Electron that contained in a conductor moved and produced electric current. The direction of current flow in a wire is opposite the flow of the electrons. Electron flows from lower to higher potential, whereas current flows from higher to lower potential. So, electric current can happen because there are potential different.

Current defined as rate amount of charge that passes though an area perpendicular to the flow of charge. Formulated as:

I=∆Q∆ t

With:Q = electric charge (C)t = time (s)I = electric current (A)

B.Resistance and Ohm Law

Ohm LawThe amount of electric current that flows is proportional to the amount of potential difference.

I ~ V

To eliminate proportionality is then necessary to add a constant that later in the know with Constant (R) so the equation becomes:

VI=R

With:V = Voltage (Volt)I = Electric Current (Ampere)R = Resistance (Ohm)

Factor that effect to resistanceSeveral factors affect the size of the electrical resistance of

a conductor wire is a type of material, length (l), cross-sectional area (A), and temperature (T). Mathematically:

R=ρ lA

With:R=Resistance (Ohm)l = length (m)p= resistivity (Ωm)A= cross-sectional area (m2)

Changing of resistivity is proportional with change of Temperature:

∆ ρ=ρ0α ∆T∨ρt=ρ0(1+α ∆T )

Changing of resistance is proportional with change of resistivity:∆ R=R0α ∆T∨R t=R0(1+α ∆T )

With:ρt= resistivity in temperature T (Ωm)ρ0= resistivity in temperature T0 (Ωm)α= coefficient of resistivity∆T= T- T0 = changing of temperature (0C)Rt= Resistance in temperature T (Ω)R0= Resistance in temperature T0 (Ω)

C.Electric CircuitjhdxiD.Ddvcd