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The mass of an electron is 9.1xx10^(-31)...

The mass of an electron is `9.1xx10^(-31)kg`. If its K.E. is `3.0xx10^(-25) J`, calculate its wavelength

Text Solution

Verified by Experts

Here, we are given: Kinetic energy, i.e., `(1)/(2) mv^(2) = 3.0 xx 10^(-25)J`
`m = 9.1 xx 10^(-31) kg, h = 6.6 xx 10^(-34) kg m^(2) s^(-1)`
`:. (1)/(2) xx (9.1 xx 10^(-31)) v^(2) = 3.0 xx 10^(25) or v^(2) = (3.0 xx 10^(-25) xx 2)/(9.1 xx 10^(-31)) = 659340 or v = 812 m s^(-1)`
`:. lamda = (h)/(mv) = (6.626 xx 10^(-34) kgm^(2) s^(-1))/((9.1 xx 10^(-31) kg) xx 812 ms^(-1)) = 8967 xx 10^(-10) m = 896.7 nm`
Alternatively, K.E. `= (1)/(2) mv^(2) or v = sqrt((2K.E.)/(m))`
`lamda = (h)/(mv) = (h)/(m) xx sqrt((m)/(2K.E.)) = (h)/(sqrt(2m xx K.E.)) = (6.626 xx 10^(-34) kg m^(2) s^(-1))/(sqrt(2 xx 9.1 xx 10^(-31) kg xx 3.0 xx 10^(-25) j)) = 8967 xx 10^(-10)m`
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The mass of an electron is 9.1 xx 10^(-31)J , if its K.E. is 3.0 xx 10^(-25)J . Calculate its wavelength.

The mass of an electron is 9.1 xx 10^(-31) kg . If its kinetic energy is 3.0 xx 10^(25) J , calculate its wavelength.

Knowledge Check

  • The mass of an electron is 9.1xx10^-31 kg and its velocity is 812 me^-1 . calculate its wavelength.

    A
    89.67nm
    B
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    C
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    D
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  • The mass of an electron is 9.1xx10^(-31) kg and velocity is 2.99xx10^(10) cm s^(-1) . The wavelenth of the electron will be

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    0.243 `"Å"`
    B
    0.0243 `"Å"`
    C
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  • The wave length of a electron with mass 9.1 xx 10^(-31)kg and kinetic energy 3.0 xx 10^(-25)J is

    A
    `89.67nm`
    B
    `8.96nm`
    C
    `456.7nm`
    D
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