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* Added Photoelectric effect equation Photoelectric effect is one of the demonstration of quanta of energy. * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * fixed doctest Co-authored-by: Rohan Anand <96521078+rohan472000@users.noreply.github.com> * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci --------- Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com> Co-authored-by: Rohan Anand <96521078+rohan472000@users.noreply.github.com>
68 lines
2.4 KiB
Python
68 lines
2.4 KiB
Python
"""
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The photoelectric effect is the emission of electrons when electromagnetic radiation ,
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such as light, hits a material. Electrons emitted in this manner are called
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photoelectrons.
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In 1905, Einstein proposed a theory of the photoelectric effect using a concept that
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light consists of tiny packets of energy known as photons or light quanta. Each packet
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carries energy hv that is proportional to the frequency v of the corresponding
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electromagnetic wave. The proportionality constant h has become known as the
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Planck constant. In the range of kinetic energies of the electrons that are removed from
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their varying atomic bindings by the absorption of a photon of energy hv, the highest
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kinetic energy K_max is :
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K_max = hv-W
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Here, W is the minimum energy required to remove an electron from the surface of the
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material. It is called the work function of the surface
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Reference: https://en.wikipedia.org/wiki/Photoelectric_effect
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"""
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PLANCK_CONSTANT_JS = 6.6261 * pow(10, -34) # in SI (Js)
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PLANCK_CONSTANT_EVS = 4.1357 * pow(10, -15) # in eVs
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def maximum_kinetic_energy(
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frequency: float, work_function: float, in_ev: bool = False
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) -> float:
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"""
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Calculates the maximum kinetic energy of emitted electron from the surface.
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if the maximum kinetic energy is zero then no electron will be emitted
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or given electromagnetic wave frequency is small.
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frequency (float): Frequency of electromagnetic wave.
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work_function (float): Work function of the surface.
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in_ev (optional)(bool): Pass True if values are in eV.
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Usage example:
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>>> maximum_kinetic_energy(1000000,2)
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0
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>>> maximum_kinetic_energy(1000000,2,True)
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0
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>>> maximum_kinetic_energy(10000000000000000,2,True)
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39.357000000000006
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>>> maximum_kinetic_energy(-9,20)
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Traceback (most recent call last):
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...
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ValueError: Frequency can't be negative.
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>>> maximum_kinetic_energy(1000,"a")
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Traceback (most recent call last):
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...
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TypeError: unsupported operand type(s) for -: 'float' and 'str'
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"""
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if frequency < 0:
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raise ValueError("Frequency can't be negative.")
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if in_ev:
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return max(PLANCK_CONSTANT_EVS * frequency - work_function, 0)
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return max(PLANCK_CONSTANT_JS * frequency - work_function, 0)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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