Photons of wavelength 115 nm are incident on a metal. The most energetic electrons ejected from the metal are bent into a circular arc of ra

Question

Photons of wavelength 115 nm are incident on a metal. The most energetic electrons ejected from the metal are bent into a circular arc of radius 1.04 cm by a magnetic field having a magnitude of 6.50 10-4 T. What is the work function of the metal?

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Thanh Hà 2 weeks 2021-07-22T08:38:05+00:00 1 Answers 8 views 0

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    2021-07-22T08:39:08+00:00

    Answer:

    6.8 eV

    Explanation:

    As you know, momentum (P) equals the mass of an object (M) times its velocity (V)

    p=mv

    Also, the momentum of the particle can be expressed in terms of the radius,

    charge and field:

    p=mv = qrB

    K.Emax = p²/2m= q²r²B²/ 2m

    K.Emax= (1.6x10^{-19})² x (0.0104)² x (6.50 x10^{-4})² / (2 x 9.1x10^{-31})

    K.E max= 1.16 x 10^{-48} / 1.82 x10^{-30

    K.Emax= 6.37 10^{-19} J

    work function ‘Ф’ = E- K.E max

    since E= hc/ λ

    Ф= hc/ λ –  K.E max => \frac{(6.63*10^{-34})(3*10^{8} ) }{115*10^{-9} } - 6.37*10^{-19}

    Ф = 1.09 x 10^{-18} J

    Ф = 1.09 x 10^{-18} / 1.6x10^{-19}

    Ф =6.8 eV

    Therefore, the work function of the metal is 6.8 eV

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