[pre-commit.ci] auto fixes from pre-commit.com hooks

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Author: pre-commit-ci[bot]

physics/photoelectric_effect.py

@@ -6,8 +6,8 @@
 In 1905, Albert Einstein explained the photoelectric effect by proposing that
 light consists of discrete packets of energy known as photons or light quanta.
 
-Each photon carries energy proportional to the frequency v of the incident 
-electromagnetic radiation. The proportionality constant h is known as 
+Each photon carries energy proportional to the frequency v of the incident
+electromagnetic radiation. The proportionality constant h is known as
 Planck's constant.
 
 The maximum kinetic energy of the emitted electrons is given by:
@@ -71,4 +71,3 @@ def maximum_kinetic_energy(
     import doctest
 
     doctest.testmod()
-