MYP Physics AC & DC Notes

How Does The Way Electric Current Flows Affect How Electricity Is Used?

1. Electric current refers to the movement of electric charge through a circuit.
2. The behaviour of electric current depends on how charges move over time.
3. Electrical systems are designed based on the type of current they use.
4. There are two main types of current used in electrical systems: direct current (DC) and alternating current (AC).

DC Means A Constant Direction (And Usually A Constant Voltage)

1. In a DC circuit, electrons move in one continuous direction.
2. The direction of charge flow does not change with time.
3. As long as the power source remains connected, the current remains steady.

Sources of Direct Current

1. Batteries and cells produce DC due to chemical reactions inside them.
2. Solar cells produce DC when light energy is converted into electrical energy.
3. Laboratory DC power supplies provide adjustable direct current.

Voltage Behaviour in DC Circuits

1. The voltage supplied by a DC source is constant.
2. Because the voltage does not change, the current in a simple DC circuit remains constant.
3. This stability makes DC suitable for precise electronic applications.

AC Means The Direction Reverses Regularly

1. In an AC circuit, electrons do not travel steadily in one direction.
2. Instead, they move back and forth around fixed positions.
3. The direction of current changes repeatedly over time.

Voltage Behaviour in AC Circuits

1. The voltage in an AC supply increases and decreases continuously.
2. The voltage passes through zero and then reverses direction.
3. This repeating change creates a regular pattern.