Question

If ${\lambda }_v,{\lambda }_x,$ and ${\lambda }_m$ represent the wavelengths of visible light, X - rays and microwaves respectively, then

• A. ${\lambda }_m>{\lambda }_x>{\lambda }_v$
• B. ${\lambda }_m>{\lambda }_v>{\lambda }_x$
• C. ${\lambda }_v>{\lambda }_x>{\lambda }_m$
• D. ${\lambda }_v>{\lambda }_m>{\lambda }_x$

Answer 1

Answer: (B)

We know that energy in terms of wavelength $\lambda$ , Planck's constant $h$ and speed of light $c$ is given by $E=\frac{hc}{\lambda }$
From above, $\Rightarrow E\propto \frac{1}{\lambda }$
Since, $E_m<E_v<E_x$
$\therefore {\lambda }_m>{\lambda }_v>{\lambda }_x$