4 Kirchhoff’s Laws and Circuit Analysis Free Online FlashCards

What does Kirchhoff’s current law state?

The total current entering a node equals the total current leaving it.

If $I_1$ and $I_2$ enter a node and $I_3$ leaves, what does KCL give?

With entering currents positive and leaving currents negative, the equation is $I_1 + I_2 - I_3 = 0$, so $I_3 = I_1 + I_2$.

What conservation principle underlies KCL?

KCL expresses conservation of electric charge: charge does not accumulate at an ordinary junction in a steady circuit.

What does Kirchhoff’s voltage law state?

The signed voltage changes around any closed loop sum to zero: $\sum \Delta V = 0$.

What conservation principle underlies KVL?

KVL expresses conservation of energy: a charge returning to its starting point has no net change in electric potential energy.

How is the voltage change across a resistor signed in a loop?

Tracing a resistor in the direction of the assumed current gives a potential change of $-IR$; tracing against it gives $+IR$.

How is an ideal source’s voltage change signed when tracing a loop?

Across an ideal source, moving from negative to positive gives $+\mathcal{E}$; moving from positive to negative gives $-\mathcal{E}$.

How many independent KCL node equations are possible for $N$ nodes?

For a network with $N$ nodes, at most $N-1$ node equations are independent.

What does a negative solved current mean?

The actual current flows opposite to the direction you assumed.

When do circuit components belong to the same node?

Components connected by ideal wire belong to the same node.

What component relation connects resistor voltage, current, and resistance?

For a resistor, use Ohm’s law, $V = IR$, with voltage polarity and current direction defined consistently.

What kind of equations describe networks of ideal voltage sources and resistors?

Networks made of ideal voltage sources and resistors have linear circuit equations.