gen-define-ac-versus-dc-and-give-one-short-worked-example-9689

Define AC versus DC and give one short worked example.

# AC versus DC **DC (Direct Current)**: Electric current that flows in one constant direction with constant polarity. The voltage remains steady over time. - Examples: Batteries, solar cells, DC power supplies **AC (Alternating Current)**: Electric current that periodically reverses direction. The voltage alternates between positive and negative in a sinusoidal pattern. - Examples: Household electricity, power grids, generators ## Worked Example **Problem**: A 120V AC outlet powers a resistive heater with resistance R = 10Ω. Find the peak voltage and RMS current. **Solution**: For AC, the standard voltage given (120V) is the RMS (root-mean-square) value. Peak voltage: $$V_{peak} = V_{RMS} \times \sqrt{2} = 120 \times 1.414 = 170V$$ RMS current using Ohm's Law: $$I_{RMS} = \frac{V_{RMS}}{R} = \frac{120V}{10Ω} = 12A$$ **Key point**: The AC voltage swings from +170V to -170V, but delivers the same average power as a 120V DC source would to the same resistor.