# HNC Electrical Principles Question - Complex waveforms and Transients HELP NEEDED!!!

Discussion in 'Homework Help' started by danfelixzs, Jun 25, 2007.

1. ### danfelixzs Thread Starter New Member

Jun 25, 2007
5
0
hello, right straight to the point, im doing an electrical engineering HNC and i've been given an assignment which needs re-doing from my 1st year...and as im not very good at organising my work or remembering last years work, ive found myself stuck on my last assignment.

its on complex waveforms and transients.

I was wondering if theres anyone who could either if their bored and got some free time...help me out with the questions...or if not point me in the right direction of some sites i can take a look at as i need to get it done this week and im lost.

Types of questions:-
Complex Waveforms
1)describe how a complex waveform can be formed an illustrate with appropriate formulae and diagrams how a complex wave may be described mathematically.

2) if a voltage waveform consists of three component waveforms described by the formula of V=150sin50t+50sin100t=20sin150t what is the RMS voltage of the waveform? why RMS voltage is more useful than the average value and what is meant by the form factor?

Transients

1) illustrate with examples how transients affect a typical RLC circuit when subjected to a DC step voltage and illustate the effect of damping on such a circuit

2) a sinusoidal voltage of v=4sin500t volts is applied at t=0 to a series L-R circuit, R=5 ohms and L=5mH. Determine an expression for the current, i flowing immediately after the application of the voltage.

Any help would be greatly appreciated, as im totally clueless, and its the last assignment of my entire 2 year course which is holding me back...

thank you

2. ### Dave Retired Moderator

Nov 17, 2003
6,960
144
For complex waveforms would they want you to look at Eulers formulas: http://en.wikipedia.org/wiki/Euler's_formula

Also look at De Moivre's formula: http://en.wikipedia.org/wiki/De_Moivre's_formula

Dave

3. ### danfelixzs Thread Starter New Member

Jun 25, 2007
5
0
i'll check them out thanks, to be honest i really can't remember, principles wasn't one of my favourite subjects and its all :S to me now!!!

thanks you for the help though

4. ### Dave Retired Moderator

Nov 17, 2003
6,960
144
If you can, get a copy of Engineering Mathematics by K.A Stroud from your college library - it will give you all you need to know about complex numbers/waveforms and their derivations.

Dave

5. ### danfelixzs Thread Starter New Member

Jun 25, 2007
5
0
wnt get a chance to get to college this week now as i am i part time student on day release...pain in the a** i no.