An ammeter with resistance `R_A` is connected in series with a resistor R, a battery of emf c and internal resistance `r`. The current measured by the ammeter is `I_A`. Find the current through the circuit if the ammeter is removed so that the battery and the resistor form a complete circuit. Express your answer in terms of `I_A, r, R_A` and `R`. Show that more "ideal" the ammeter, the smaller the difference between this current and the current `I_A`. ltbr. (b) If `R = 3.80 Omega, epsilon = 7.50 V` and `r = 0.45 Omega`, find the maximum value of the ammeter resistance `R_A` so that `I_A` is within `99%` of the current in the circuit when the ammeter is absent. (c) Explain why your answer in part (b) represents a maximum value.