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We wish to see inside an atom. Assuming ...

We wish to see inside an atom. Assuming the atom to have a diameter of `100` pm, this means that one must be able to resolve a width of say `10` pm. If an electron microscope is used, the minimum electron energy required is about

A

1.5 KeV

B

15 KeV

C

150 KeV

D

1.5 KeV

Text Solution

Verified by Experts

The correct Answer is:
B
The wave nature of electron [de broglie waves ] is used in the construction of an electron microscope .
`lamda = (h)/(mV) = (h)/(sqrt(2mK)) therefore lamda^2 = (h^2)/(2mK)`
where K is the K.E. of the electron
`therefore K= (h^2)/(2mlamda^2)`
`= ((6.6xx10^(-34))^2)/(2xx9.1xx10^(-31)xx(10xx10^(-12))^2) J`
`= (6.6xx6.6xx10^(-15))/(2xx9.1xx1.6xx10^(-19)) eV`
`=15xx10^3 eV = 15 KeV`
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