Integration question (average voltage)

[ckeller]

Homework Statement

The voltage at a point in a circuit is represented by the function v = 15 sin (200πt) volts. Use integration methods to calculate;

(a) The average voltage between t = 5ms and t = 10ms
(b) The average voltage between t = 0 and t = 10ms
(c) The r.m.s. voltage between t = 5ms and t = 15ms

Homework Equations

The Attempt at a Solution

I'm not too sure I understand the question properly, could anyone help at all?

 

[Char. Limit]

The average value of a function f(x) over an integral [a,b] is such:

$$Avg = \frac{1}{b-a} \int_a^b f(x) dx$$

See how you can use this to help you?

 

[ckeller]

The average value of a function f(x) over an integral [a,b] is such:

$$Avg = \frac{1}{b-a} \int_a^b f(x) dx$$

See how you can use this to help you?

Oh yeah thanks, that is useful to know! so I don't need to integrate 15sin(200PIt)?

 

[ckeller]

I got [15-cos(200pit)/pi + C] does that look right?

And then calculate between 5 and 10 ms

 

[SammyS]

Oh yeah thanks, that is useful to know! so I don't need to integrate 15sin(200PIt)?

Yes, you need to integrate.

Char. Limit has given you a method for finding the average of a function. That method has an integral.

 

[asitiaf]

what is wrong if you integrate the functions in the limit specified?

 

[SammyS]

what is wrong if you integrate the functions in the limit specified?

Could you please clarify your question ?