Voltage Sources

Formula

A rule that relates physical quantities using equations, inequalities, or mathematical descriptions.

Definition

Formula Type Invented to define a new concept

Law

Formula Type that Describes a relationship in nature

Derivation

Formula Type that is Obtained through mathematical manipulation

Ideal DC Voltage Source

A theoretical source that produces a constant load voltage regardless of load resistance.

Effect of Load Resistance (Ideal Source)

Changing the load resistance affects only the current, not the voltage.

Second Approximation Voltage Source

A more realistic model that includes a source resistance R_s in series with the ideal source.

V_L = V_S - (I_L)(R_S)

Load Voltage (Second Approximation)

I_L = (V_S)/(R_S + R_L)

Load Current in a Voltage Divider

Stiff Voltage Source

A source whose internal resistance is small enough that it can be ignored

100

The load resistance must be at least ___ times larger than the source resistance.

Stiff Region

The range region on the graph where load voltage remains nearly constant because R_L » R_S

Low-Frequency Validity

Second approximation is valid only at low frequencies

Lead Inductance and Stray Capacitance

2 things that become significant at high frequencies