What occurs when the phase angle between voltage and current is at 0 degrees?

When the phase angle between voltage and current is at 0 degrees, it indicates that the voltage and current are in perfect sync with each other, meaning they reach their maximum and minimum values simultaneously. This scenario occurs in a purely resistive load where the resistance is the only factor affecting the circuit's behavior. In such a case, all the supplied power is effectively converted into work or heat, with no reactive components (like inductance or capacitance) present to cause phase shifts.

In a purely resistive circuit, the relationship can be expressed mathematically as the current being directly proportional to the voltage according to Ohm’s law, (I = V/R). Therefore, since the current and voltage rise and fall together, this condition of a 0-degree phase angle is solely representative of a resistive load. In contrast, inductive loads lead to a phase shift where the current lags the voltage, and capacitive loads result in a phase shift where the current leads the voltage, which is not the case when the phase angle is zero. Excessive voltage, while potentially misleading, does not correlate specifically with the phase angle's relation to current and voltage.