6 Introductory Electrical Systems Free Online FlashCards

What are the main parts of an electrical system?

An electrical system connects a source, conductors, a load, controls, and protective devices. Current can flow when the conducting path is complete.

What is voltage?

Voltage is the electric potential difference that can drive charge through a circuit. It is measured in volts (V).

What does electric current measure?

Current is the rate of flow of electric charge. It is measured in amperes (A).

What does electrical resistance describe?

Resistance describes how strongly a component opposes current. It is measured in ohms (Ω).

State Ohm’s law for an ohmic component.

For an ohmic component, Ohm’s law is $V = IR$: voltage equals current multiplied by resistance.

What is electrical power, and how is it calculated for a resistive load?

Electrical power is the rate of energy transfer. For a resistive load, $P = VI$, and equivalently $P = I^2R$ or $P = \frac{V^2}{R}$.

What allows current to flow through a circuit?

A closed circuit has a complete conducting path, so current can flow.

How do fuses and circuit breakers protect a circuit?

A fuse or circuit breaker opens a circuit when current exceeds a safe value for long enough. It must be selected to protect conductors and equipment.

How does current behave in a series path, and how do its resistances combine?

In a series path, the same current passes through each component, and the component resistances add: $R_{\text{total}} = R_1 + R_2 + \cdots$.

What voltage and current relationships apply to parallel branches?

Parallel components connect across the same two nodes, so each branch has the same voltage. Total current is the sum of the branch currents.

What does Kirchhoff’s current law state?

Kirchhoff’s current law states that the total current entering a junction equals the total current leaving it.

What does Kirchhoff’s voltage law state?

Kirchhoff’s voltage law states that the signed voltage changes around any complete loop add to zero.