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?