Add Ideal Gas Law for physics

physics/ideal_gas_law.py

@@ -0,0 +1,51 @@
+"""
+The ideal gas law, also called the general gas equation, is the
+equation of state of a hypothetical ideal gas. It is a good approximation
+of the behavior of many gases under many conditions, although it has
+several limitations. It was first stated by Benoît Paul Émile Clapeyron
+in 1834 as a combination of the empirical Boyle's law, Charles's law,
+Avogadro's law, and Gay-Lussac's law.[1] The ideal gas law is often written
+in an empirical form:
+ ------------
+ | PV = nRT |
+ ------------
+P	=	Pressure (Pa)
+V	=	Volume (m^3)
+n	=	Amount of substance (mol)
+R	=	Universal gas constant
+T	=	Absolute temperature (Kelvin)
+
+(Description adapted from https://en.wikipedia.org/wiki/Ideal_gas_law )
+"""
+
+UNIVERSAL_GAS_CONSTANT = 8.314462  # Unit - J mol-1 K-1
+
+
+def pressure_of_gas_system(moles: float, kelvin: float, volume: float) -> float:
+    """
+    >>> pressure_of_gas_system(2, 100, 5)
+    332.57848
+    >>> pressure_of_gas_system(0.5, 273, 0.004)
+    283731.01575
+    """
+    if moles < 0 or kelvin < 0 or volume < 0:
+        raise Exception("Invalid inputs. Enter positive value.")
+    return moles * kelvin * UNIVERSAL_GAS_CONSTANT / volume
+
+
+def volume_of_gas_system(moles: float, kelvin: float, pressure: float) -> float:
+    """
+    >>> volume_of_gas_system(2, 100, 5)
+    332.57848
+    >>> volume_of_gas_system(0.5, 273, 0.004)
+    283731.01575
+    """
+    if moles < 0 or kelvin < 0 or pressure < 0:
+        raise Exception("Invalid inputs. Enter positive value.")
+    return moles * kelvin * UNIVERSAL_GAS_CONSTANT / pressure
+
+
+if __name__ == "__main__":
+    from doctest import testmod
+
+    testmod()