Q.What are the advantages and disadvantages of Alternating Current System over Direct Current System ?

AC is preferred for generation and long-distance transmission because transformers make voltage easily adjustable, while DC is required for certain applications like electrolysis and offers a simpler, purely resistive circuit analysis.

Advantages of AC over DC

1. AC voltage can be easily stepped up or down using transformers, allowing transmission at very high voltage (low current, hence low $I^2R$ transmission loss) and safe stepping-down for domestic/industrial use.
2. AC is easier and cheaper to generate in bulk (large AC generators/alternators) and AC motors are generally simpler, more robust, and cheaper than DC motors.
3. AC can be readily converted to DC (via rectifiers) when DC is needed, but the reverse (DC to variable-voltage AC) is comparatively harder/costlier.

Disadvantages of AC compared to DC

1. AC is generally considered more dangerous at the same rms voltage/power due to its oscillating nature affecting the human body's nerve/muscle response differently.
2. AC cannot be used directly for processes like electrolysis, electroplating, or charging batteries/capacitors for storage, which require a steady, unidirectional current. …

AC's ability to be transformed to any voltage makes long-distance transmission efficient and its generators/motors simpler, but it cannot directly perform DC-only tasks like electrolysis or battery charging, and poses greater shock hazard at a given peak voltage.

Advantages of AC over DC

1. AC voltage can be stepped up or down easily and efficiently using a transformer, which has no moving parts and very high efficiency; this allows electrical power to be transmitted at very high voltage (hence low current, low $I^2R$ loss) over long distances and then stepped down for safe local use — DC cannot be transformed this simply.
2. AC generators (alternators) are simpler in construction, cheaper, and more robust than DC generators (which need a commutator and brushes that wear out and cause sparking).
3. AC motors (especially induction motors) are simpler, cheaper, more reliable, and need less maintenance than DC motors.
4. AC can be easily converted to DC (using rectifiers) when DC is needed, but the reverse (DC to AC) needs comparatively more complex inverter circuitry.

Disadvantages of AC compared to DC

1. AC cannot be used directly for processes that need a steady unidirectional current, such as electroplating, electrolysis, or charging storage batteries — it must first be rectified to DC. …