Electrical Theory & Principles Flashcards

A transformer has a turns ratio of 10:1 (primary to secondary). If the primary voltage is 480V, what is the secondary voltage?

Answer: 48 V

Secondary voltage = Primary voltage / Turns ratio = 480 / 10 = 48V, as voltage is proportional to turns ratio.

Skin effect in AC conductors causes current to concentrate:

Answer: Toward the outer surface of the conductor

At higher AC frequencies, eddy currents force the current toward the conductor's outer surface, increasing effective resistance.

Norton's equivalent circuit consists of:

Answer: A current source in parallel with a resistance

Norton's Theorem represents any linear network as an equivalent current source (I_N) in parallel with a resistance (R_N).

The relationship between charge (Q), capacitance (C), and voltage (V) is:

Answer: Q = C × V

The fundamental capacitor equation Q = CV shows that stored charge is proportional to both capacitance and voltage.

When a conductor moves through a magnetic field, an EMF is induced. This is described by:

Answer: Faraday's Law of Electromagnetic Induction

Faraday's Law states that the induced EMF equals the rate of change of magnetic flux linkage through the conductor.

In a delta-connected three-phase load, the relationship between line current and phase current is:

Answer: I_line = I_phase × √3

In a delta connection, line current = phase current × √3, while line voltage equals phase voltage.

The superposition theorem states that in a linear circuit with multiple sources, the total response is:

Answer: The algebraic sum of responses due to each source acting alone

Superposition allows each independent source to be analyzed separately (others replaced by their internal impedances) and results summed.