feat: add get_photon_frequency to light in celerity module

src/celerity/light.py

@@ -10,6 +10,7 @@
 
 # **************************************************************************************
 
+
 def get_light_travel_distance(time: float) -> float:
     """
     Calculate the distance light travels in a given time.
@@ -19,4 +20,24 @@ def get_light_travel_distance(time: float) -> float:
     """
     return SPEED_OF_LIGHT * time
 
-# **************************************************************************************
+
+# **************************************************************************************
+
+
+def get_photon_frequency(
+    wavelength: float,
+) -> float:
+    """
+    Calculate the frequency of a photon given its wavelength (in m).
+
+    :param wavelength: Wavelength in meters
+    :return: Photon frequency in Hz
+    :raises ValueError: If wavelength is less than or equal to zero
+    """
+    if wavelength <= 0:
+        raise ValueError("Wavelength must be a positive number.")
+
+    return SPEED_OF_LIGHT / wavelength
+
+
+# **************************************************************************************

tests/test_light.py

@@ -8,10 +8,11 @@
 
 import unittest
 
-from celerity.light import get_light_travel_distance
+from celerity.light import get_light_travel_distance, get_photon_frequency
 
 # **************************************************************************************
 
+
 class TestLightTravelDistance(unittest.TestCase):
     def test_light_travel_distance(self):
         """
@@ -33,4 +34,36 @@ def test_light_travel_distance(self):
         expected_distance = 149896229.0  # Speed of light in m/s * 0.5 seconds
         self.assertAlmostEqual(get_light_travel_distance(time), expected_distance)
 
-# **************************************************************************************
+
+# **************************************************************************************
+
+
+class TestPhotonFrequency(unittest.TestCase):
+    def test_photon_frequency(self) -> None:
+        """
+        Test the photon frequency calculation.
+        """
+        # Calculate the frequency using the wavelength of 500 nm:
+        frequency = get_photon_frequency(500e-9)
+
+        # Expected approximate frequency in Hz for 500 nm wavelength:
+        expected_frequency = 6e14
+
+        self.assertAlmostEqual(
+            frequency, expected_frequency, delta=1e-3 * expected_frequency
+        )
+
+    def test_negative_photon_frequency(self) -> None:
+        """
+        Test the photon frequency calculation with a negative wavelength.
+        """
+        with self.assertRaises(ValueError):
+            get_photon_frequency(-500e-9)
+
+
+# **************************************************************************************
+
+if __name__ == "__main__":
+    unittest.main()
+
+# **************************************************************************************