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Consider figure for photoemission. How w...

Consider figure for photoemission. How would you reconcile with momentum-conservation? Note light (photons) have momentum in a different direction than the emitted electrons.

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During photoelectric emission, the momentum of incident photon is transfered to the metal. At microscopic level, atoms of a metal absorb the photon and its momentum is transfered mainly to the nucleus and electrons. The electron excited is emitted. Therefore, the conservation of momentum is to be considerd as the momentum of incident photon transfered to the nucleus and electrons.
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Consider figure for photoemission. How would you reconcile with momentum-conservatin? Note light (photons) have momentum in a different direction than the emitted electrons.

A parallel beam of electrons , travelling in x - direction , falls on a slit of width d (see the figure) . If after passing the slit, an electron acquires momentum P_y in the y direction, then for a majority of electrons passing through the slit , (h is Planck's constant)

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The momentum of a photon having energy equal to the rest energy of an electron is

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Knowledge Check

  • A parallel beam of electrons travelling in X-direction falls on a slit of width d (see figure). If after passing the slit, an electron acquires momentum p_y in the Y-direction, then for a majority of electrons passing through the slit (h is Planck's constant):

    A
    `|p_y|d = h`
    B
    `|p_y|d gt h`
    C
    `|p_y|d lt h`
    D
    `|p_y|d gt gt h`

  • A parallel beam of electrons travelling in x-direction falls on a slit of width d (see figure). If after passing the slit, an electron acquires momentum p_y in the y-direction then for a majority of electrons passing through the slit (h is Planck's constant):

    A
    `|P_y|d gt h`
    B
    `|P_y| d lt h`
    C
    `|P_y|d = h`
    D
    `|P_y| d gt gt h`

  • The momentum of a photon having energy equal to the rest energy of an electron is

    A
    zero
    B
    `2.73 xx 10^(-22)kg ms^(-1)`
    C
    `1.99 xx 10^(-24)kg ms^(-1)`
    D
    infinite