def test_gauss_1d_dielectric():
pp = ParallelPlates((2.0, 4.0), (3e-3, 2e-3))
X, er = pp.get_arrays(101)
v1 = 10.0
V = pp.potential(X, v1)
Q = np.array([fdm.gauss_1d(X, V, er, i) for i in range(1, len(X) - 1)])
Qa = pp.charge(v1)
assert Q == approx(Qa)
def test_charge():
pp = ParallelPlates(3.5, 1e-3)
Va = 10.0
expected = pp.capacitance() * Va
assert pp.charge(Va) == approx(expected)