Answer
(a) $R = 15~\Omega$
(b) $R = 10~\Omega$
Work Step by Step
(a) We can find the resistance at point 1:
$V = I~R$
$R = \frac{V}{I}$
$R = \frac{0.3~V}{0.02~A}$
$R = 15~\Omega$
(b) We can find the resistance at point 2:
$V = I~R$
$R = \frac{V}{I}$
$R = \frac{0.4~V}{0.04~A}$
$R = 10~\Omega$
