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Direct-current circuits
Second Kirchhoff rule (circuit rule)
EMF of source
U
src
=
V
x
nV
μV
mV
V
kV
MV
current in circuit
I
=
A
x
pA
nA
μA
mA
A
kA
internal resistance of voltage source
R
int
=
Ω
x
μΩ
mΩ
Ω
kΩ
MΩ
GΩ
TΩ
resistance of external circuit
R
ext
=
Ω
x
μΩ
mΩ
Ω
kΩ
MΩ
GΩ
TΩ
1. Define values of all variables, besides sought quantity
2. Change units if necessary
3. Click "Calculate"