Question

A beam of electrons accelerated by a large potential difference V is made to strike a metal target to produce X-rays. For which of the following values of V, the resulting X-rays have the lowest minimum wave length:

• A. 10 KV
• B. 20 KV
• C. 30 KV
• D. 40 KV

Answer 1

The correct option is D 40 KV

More is the potential difference by which the electron has accelerated, more is the energy of the X-rays emitted.
Wavelength of X-rays emitted $\lambda =\frac{hc}{E}$
where $E$ is the energy of X-rays emitted.
$⟹\lambda \propto \frac{1}{E}$
Thus X-rays have the lowest minimum wave length if the potential difference is maximum i.e. $40kV$