Question

The electron beam in a colour TV is accelerated through some $\text{kilovolts}$ and then strikes the screen. If the wavelength of the most energetic X-ray photon is $20\text{nm}$, calculate its energy. Given: $hc=1242\text{eV-nm}$

• A. $6.2\text{eV}$
• B. $62\text{eV}$
• C. $42\text{eV}$
• D. $72\text{eV}$

Answer 1

The correct option is B $62\text{eV}$

As we know that,

$E=\frac{hc}{\lambda }$

$E=\frac{1242}{20}=62.1\text{eV}\approx 62\text{eV}$

Hence, option $\left(\text{B}\right)$ is correct.