Calculating Mean Square Value of a Thermoelectric Ammeter Circuit

[MissP.25_5]

I don't understand a few things here.

Firstly, here's the question:

This is thermoelectric ammeter. Internal resistance can be ignored.
1. Find the mean square value of the circuit.
2. Find the value that is displayed on the ammeter (alternating current).

In the textbook, the formula for the mean square value of a periodic signal is given -T/2 to T/2 as the integral region but here in the answer given, it's from 0 to T. Why?

And how come the final answer for number 1 differs from i^2?

 

[NascentOxygen]

Hi MissP. It doesn't matter what the region is, so long as it covers one complete cycle of the periodic waveform. You can choose whatever end-points you like, or just whatever is convenient. The average over any duration of T will be the same, wherever you choose as the starting point. (If it isn't, then it's not a periodic wave.)

I'm guessing that you are determining the RMS value of a wave comprising a sine wave plus some of its second harmonic?