In an electron microscope, the resolution that can be achieved is of the order of the wavelength of electrons used. To resolve a width of `7.5 xx 10^(-12)` m, the minimum electron energy required is close to :

Options

A. 1keV
B. 5keV
C. 500 keV
D. 100 keV

Answer

B

Explanation

`lamda = (h)/(mV) = (h)/(sqrt(2mE)) = (12.27)/(sqrtV) A^@ rArr 0.175 = (12.27)/(sqrtV) rArr sqrtV = (12270)/(175) rArr V = (70)^2 = 4900 V rArr E~ 5keV`