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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,then calculate it's wavelength

A

`857.6 nm`

B

`896.7 nm`

C

`845.5 nm`

D

`860 nm`

Text Solution

Verified by Experts

The correct Answer is:
B
Since `K.E. =(1)/(2) mv^(2)`
`therefore v=((2 K.E.)/(m))^((1)/(2)) =((2xx3.0xx10^(-25) kg m^(2)s^(2))/(9.1xx10^(-31) kg))^((1)/(2))=812 ms^(-1)`
`lamda =(h)/(mv) =(6.626xx10^(-34) Js)/((9.1xx10^(-31) kg) (812 ms^(-1)))=8967xx10^(-10) m=896.7 nm`
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