Post a New Question

physics

posted by .

if electron are caused to fall through a potential difference of 100000 voltage , determine their final speed if they were initially at rest.

  • physics -

    e*100,000 is the kinetic energy.
    e is the electron charge,1.6*10^-19 C

    Set 100,000*e equal to (1/2)mV^2 and solve for V

    m is the electron mass.

  • physics -

    6646

  • physics -

    p.d.=100000V
    therefore, workdone , W=q×p.d.
    W=1.6×10^-19 × 100000
    =1.6×10^-14 Joules
    since work done = force × displacement
    F×s=1.6×10^-14
    m×a×s=1.6×10^-14
    9.1×10^-31×a×s=1.6×10^-14
    a×s=(1.6×10^-14)÷(9.1×10^-31)
    a×s=1.75×10^17
    v^2/2=1.75×10^17
    v=5.09×10^8m/s

  • physics -

    Recall that one electron-volt is the energy gained by an electron in moving through a potential difference of 1 V, so
    1 eV = 1.6 * 10^-19 Joules
    1,000,000 V = 1.6 ^ 10^-19 * 10^6 Joules = 1.6 * 10^-13 J
    So this must be the kinetic energy gained be the electron.
    KE = (1/2) m v^2
    From reference tables
    mass of electron = 9.11 * 10^-31 kg
    So
    1.6 * 10^-13 = (1/2) * 9.11 * 10^-31 * v^2
    v^2 = 2 * 1.6 * 10^-13 / 9.11 * 10^-31 = 0.35 * 10^18
    v = 0.59 * 10^9 m/s

Answer This Question

First Name
School Subject
Your Answer

Related Questions

More Related Questions

Post a New Question