Question

An electron beam after collision with the target produces X-rays of wavelength $4A^0$. The velocity of the electron beam is

• A. $3.31\times {10}^{7}m/s$
• B. $6.31\times {10}^{7}m/s$
• C. $8.31\times {10}^{7}m/s$
• D. $9.31\times {10}^{7}m/s$

Answer 1

Answer: (B)

$6.31\times {10}^{7}m/s$

Energy of x-ray beam $=\frac{hc}{\lambda }=4.95\ast {10}^{-16}J=\frac{1}{2}m{v}^2$ and it gives $v=6.31\ast {10}^7$ m/s.

So, the answer is option (B).