Hey there! Sign in to join this conversationNew here? Join for free

photoelectric effect (need help) Watch

Announcements
    • Thread Starter
    Offline

    1
    ReputationRep:
    so i need help with this question and im too frustrated to think straight, i think i have some answers but there probably wrong. So here it is

    The stopping potential when a frequency of 1.61*10^15 Hz is shone on a metal is 3V

    a) what is energy transferred by each photon ?
    b)calculate the work function of the metal
    c)What is the maximum speed of the ejected electrons
    Offline

    2
    ReputationRep:
    (Original post by nebbercracker)
    so i need help with this question and im too frustrated to think straight, i think i have some answers but there probably wrong. So here it is

    The stopping potential when a frequency of 1.61*10^15 Hz is shone on a metal is 3V

    a) what is energy transferred by each photon ?
    b)calculate the work function of the metal
    c)What is the maximum speed of the ejected electrons
    Right down the answers you have got, and I'll see if they match with mine. Also did you use the correct equations? And if you did, what equations did you use?
    • Thread Starter
    Offline

    1
    ReputationRep:
    (Original post by Reety)
    Right down the answers you have got, and I'll see if they match with mine. Also did you use the correct equations? And if you did, what equations did you use?
    well for part a i did E=hv so energy = planks * velocity which for a photon is the speed of light

    6.63*10^-34 x 300,000,000 m/s = 1.989*10^-25

    then for part b i used the equation work function = hf-E so planks * frequency - energy

    6.63*10^-34 x 1.61*10^15 - 1.989*10^-25 = 1.0674*10^-18

    for part c I didn't know what equation to use and it was pretty late at night when i attempted all this so i gave up.
    So do these two answers seem right ?
    • Aston Villa FC Supporter
    Offline

    3
    ReputationRep:
    (Original post by nebbercracker)
    so i need help with this question and im too frustrated to think straight, i think i have some answers but there probably wrong. So here it is

    The stopping potential when a frequency of 1.61*10^15 Hz is shone on a metal is 3V

    a) what is energy transferred by each photon ?
    b)calculate the work function of the metal
    c)What is the maximum speed of the ejected electrons
    a) E = hf
    b) E_kmax = hf - (phi)
    c) E)kmax = hf - (phi) where E_kmax = 1/2 m v^2
    Offline

    11
    ReputationRep:
    (Original post by nebbercracker)
    so i need help with this question and im too frustrated to think straight, i think i have some answers but there probably wrong. So here it is

    The stopping potential when a frequency of 1.61*10^15 Hz is shone on a metal is 3V

    a) what is energy transferred by each photon ?
    b)calculate the work function of the metal
    c)What is the maximum speed of the ejected electrons
    a) E = hf

    b) hf = work function - KE (max) ==> KE (max) = work function - hf

    However, the KE (max) of the electron = eV, where V is the stopping potential.

    Therefore, KE max = 1.6 x 10^(-19) x 3

    c) KE max = 0.5 x m x v^2, and just rearrange to find v.
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Break up or unrequited love?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.