What does a decrease in voltage to 50% do to power consumption according to the principles of electrical theory?

• A. Power remains the same
• B. Power increases by 100%
• C. Power decreases to 25% of the original
• D. Power doubles

Answer: (C)

In electrical theory, the relationship between voltage, current, and power can be understood using the formula for electrical power, which is given by P = V × I, where P is power, V is voltage, and I is current. When voltage is decreased to 50% of its original value, the impact on power consumption depends on how the circuit behaves.

Assuming a resistive load where resistance remains constant, if the voltage is halved, the current will also decrease. Ohm's Law states that I = V/R; therefore, if V is reduced to half and R remains the same, the current will also be halved. Consequently, when you apply this change to the power formula:

New Power, P' = (V/2) × (I/2) = (1/2) × (1/2) × (V × I) = (1/4) × P

This indicates that the new power consumption becomes 25% of the original power level when the voltage is reduced to half. Hence, the correct understanding is that power consumption decreases to 25% of the original value when voltage is decreased to 50%.