AC & DC Flashcards

All 6 cards in this deck

What is direct current (d.c.)?

A movement of charge in one direction only.

What is alternating current (a.c.)?

A current in which the movement of charge repeatedly changes direction.

What type of current do cells and batteries supply?

Direct current (d.c.).

What is the difference between a direct voltage and an alternating voltage?

A direct voltage keeps the same polarity (positive stays positive); an alternating voltage repeatedly swaps polarity, so it pushes charge first one way then the other.

On an oscilloscope or voltage–time graph, how can you tell an a.c. supply from a d.c. supply?

a.c. gives a repeating wave that goes above and below zero; d.c. gives a flat horizontal line at a constant value.

True or false? The current from a cell changes direction 50 times every second.

False. A cell supplies d.c., which flows in one direction only; it is UK mains a.c. that alternates, at 50 Hz.