If Planck's constant is given as `6.4xx10^(-34)J`and electron charge is `1.6xx10^(-19)`C, the maximum wavelength of X-ray emitted ,when a 10keV electron is completely stopped by a target is

Options

A. 6.2Å
B. 3.4Å
C. 1.8Å
D. 1.2Å

Answer

D

Explanation

Planck's constant ,`h=6.4xx10^(-34)J-s`
Electron change ,`e =1.6xx10^(-19)C`
Energy of electron ,E =10KeV
The expression for maximum wavelength of X-rays emitted is given as ,
`lamda_(max)=(hc)/(E) =((6.4xx10^(-34))xx(3xx10^(8)))/(10xx10xx1.6xx10^(-16)``thereforelamda_(max)=(19.2xx10^(-11))/(1.6)=1.2xx10^(-10)=1.2A^(o)`