# What is the name for a pulse of current?

1. May 31, 2012

A steady state electrical current is called DC. A periodic rising and falling current is called AC. What is a single-polarity pulse of rising current ( a single rectified hump of a sine wave e.g.) called? AC? DC? or something else?

2. May 31, 2012

### Staff: Mentor

3. May 31, 2012

### vk6kro

DC is a unidirectional current (or voltage) but not necessarily a constant one.
http://en.wikipedia.org/wiki/DC_current

An AC current or voltage is not a rising and falling one. It is one which changes polarity from positive to negative to positive and so on.

A pulse which does not change polarity but changes amplitude is just a DC pulse. However this needs to be supplemented with information about rise time, duration, fall time, repetition rate etc.

4. Jun 1, 2012

### cabraham

Current spike.

Claude

5. Jun 2, 2012

### sophiecentaur

A step function is often called a Heaviside Function.

DC means, strictly, an unchanging value of current. Unidirectional current may be referred to as DC but it is sloppy terminology and leads to confusion. If you want to avoid confusion then don't refer to anything other than DC as DC. (despite what may be written in wiki or elsewhere) A current that is always positive but has a varying value is a combination of DC and AC ('ripple'). If you state it that way then there can be no confusion.