* Medium
"""
from sympy.physics.units import second, meter, kilogram, ampere
__all__ = ['Medium']
from sympy.core.basic import Basic
from sympy.core.symbol import Str
from sympy.core.sympify import _sympify
from sympy.functions.elementary.miscellaneous import sqrt
from sympy.physics.units import speed_of_light, u0, e0
c = speed_of_light.convert_to(meter / second)
_e0mksa = e0.convert_to(ampere**2 * second**4 / (kilogram * meter**3))
_u0mksa = u0.convert_to(meter * kilogram / (ampere**2 * second**2))
class Medium(Basic):
"""
This class represents an optical medium. The prime reason to implement this is
to facilitate refraction, Fermat's principle, etc.
Explanation
===========
An optical medium is a material through which electromagnetic waves propagate.
The permittivity and permeability of the medium define how electromagnetic
waves propagate in it.
from sympy import sqrt, simplify
from sympy.physics.optics import Medium
from sympy.abc import epsilon, mu
from sympy.physics.units import speed_of_light, u0, e0, m, kg, s, A
c = speed_of_light.convert_to(m/s)
e0 = e0.convert_to(A**2*s**4/(kg*m**3))
u0 = u0.convert_to(m*kg/(A**2*s**2))
def test_medium():
m1 = Medium('m1')
assert m1.intrinsic_impedance == sqrt(u0/e0)
assert m1.speed == 1/sqrt(e0*u0)
assert m1.refractive_index == c*sqrt(e0*u0)
assert m1.permittivity == e0
assert m1.permeability == u0
m2 = Medium('m2', epsilon, mu)
assert m2.intrinsic_impedance == sqrt(mu/epsilon)
assert m2.speed == 1/sqrt(epsilon*mu)
assert m2.refractive_index == c*sqrt(epsilon*mu)
assert m2.permittivity == epsilon
assert m2.permeability == mu
# Increasing electric permittivity and magnetic permeability
# by small amount from its value in vacuum.
m3 = Medium('m3', 9.0*10**(-12)*s**4*A**2/(m**3*kg), 1.45*10**(-6)*kg*m/(A**2*s**2))
assert m3.refractive_index > m1.refractive_index
assert m3 > m1
# Decreasing electric permittivity and magnetic permeability
# by small amount from its value in vacuum.
* Medium
"""
from __future__ import division
from sympy.physics.units import second, meter, kilogram, ampere
__all__ = ['Medium']
from sympy import Symbol, sympify, sqrt
from sympy.physics.units import speed_of_light, u0, e0
c = speed_of_light.convert_to(meter/second)
_e0mksa = e0.convert_to(ampere**2*second**4/(kilogram*meter**3))
_u0mksa = u0.convert_to(meter*kilogram/(ampere**2*second**2))
class Medium(Symbol):
"""
This class represents an optical medium. The prime reason to implement this is
to facilitate refraction, Fermat's priciple, etc.
An optical medium is a material through which electromagnetic waves propagate.
The permittivity and permeability of the medium define how electromagnetic
waves propagate in it.
Parameters
==========