Answer
We can rank the currents in order from largest to smallest:
$I_c \gt I_a = I_d \gt I_b$
Work Step by Step
We can find the current in each case:
(a) $I_a = \frac{V}{R} = \frac{2~V}{2~\Omega} = 1~A$
(b) $I_b = \frac{V}{R} = \frac{1~V}{2~\Omega} = \frac{1}{2}~A$
(c) $I_c = \frac{V}{R} = \frac{2~V}{1~\Omega} = 2~A$
(d) $I_d = \frac{V}{R} = \frac{1~V}{1~\Omega} = 1~A$
We can rank the currents in order from largest to smallest:
$I_c \gt I_a = I_d \gt I_b$
