Question

The ratio of the energy of the photon of $2000\stackrel{o}{A}$ wavelength to that of $4000\stackrel{o}{A}$ wavelength is:

• A. $1:4$
• B. $4:1$
• C. $1:2$
• D. $2:1$

Answer 1

The correct option is D $2:1$

$E=hv$; $E=\frac{hC}{\lambda }$
$\therefore$ Energy of photon is inversely proportional to wavelength.
$E\alpha \frac{1}{\lambda }$
If ${\lambda }_1=2000\stackrel{o}{A};{\lambda }_2=4000\stackrel{o}{A}$
$\frac{E_1}{E_2}=\frac{{\lambda }_2}{{\lambda }_1}=\frac{4000}{2000}=\frac{2}{1}$
$\therefore$ The ratio of the energy of photon of $2000\stackrel{o}{A}$ wavelength to that of $4000\stackrel{o}{A}$ wavelength is $2:1.$