$(a)$ What are the values of $mA$ and $\mu A$ in terms of Ampere $(A)$?
$(b)$ Draw the symbols of a battery and a rheostat.

(N/A) The values are as follows:
$1 \text{ mA (milliampere)} = 10^{-3} \text{ A} = \frac{1}{1000} \text{ A}$
$1 \text{ } \mu\text{A (microampere)} = 10^{-6} \text{ A} = \frac{1}{1000000} \text{ A}$
$(b)$ The symbols for a battery and a rheostat are shown in the image provided.