I am currently working my way through Electrical Installation Calculations 7th Edition and have got to exercise 6 regarding AC waveforms. the question is as follows
An alternating current has the following values taken at intervals of 30 degrees over 1 half cycle
angle ° current A
0----------0
30---------10.5
60---------17.5
90---------19.7
120--------150
150--------11.5
180--------0
Determine the rms and average values of this current.
I calculate that for a Sinusoidal waveform 90° (peak) x 0.707=rms so 19.7x0.707= 13.93A
and 90° (peak) x 0.637=average so 19.7x0.637= 12.55A
however the answers in the book are given as 31.1A and 14.1A
Can any of you knowledgeable folk help me out please
An alternating current has the following values taken at intervals of 30 degrees over 1 half cycle
angle ° current A
0----------0
30---------10.5
60---------17.5
90---------19.7
120--------150
150--------11.5
180--------0
Determine the rms and average values of this current.
I calculate that for a Sinusoidal waveform 90° (peak) x 0.707=rms so 19.7x0.707= 13.93A
and 90° (peak) x 0.637=average so 19.7x0.637= 12.55A
however the answers in the book are given as 31.1A and 14.1A
Can any of you knowledgeable folk help me out please