Question

An X-ray tube is operated at 15 kV. Calculate the upper limit of the speed of the electrons striking the target.

• A. $7.26\times {10}^{7}m/s$
• B. $7.62\times {10}^{7}m/s$
• C. $7.62\times {10}^{7}cm/s$
• D. $7.26\times {10}^{9}m/s$

Answer 1

Answer: (A)

$7.26\times {10}^{7}m/s$

By conserving energy:

$15\times {10}^{3}eV=\frac{m{v}^2}{2}$

$15\times {10}^3\times 1.6\times {10}^{-19}=\frac{9.1\times {10}^{-31}{v}^2}{2}$

$v=7.26\times {10}^{7}m/s$