Physics - Modern Physics Question with Solution | TestHub

According to Einstein's photoelectric equation:

$E_1=\frac{hc}{{\lambda }_1}-W$

$E_2=\frac{hc}{{\lambda }_2}-W$

Multiplying the first equation by ${\lambda }_1$ and the second by ${\lambda }_2$:

$E_1{\lambda }_1=hc-W{\lambda }_1$

$E_2{\lambda }_2=hc-W{\lambda }_2$

Subtracting the second equation from the first:

$E_1{\lambda }_1-E_2{\lambda }_2=W{\lambda }_2-W{\lambda }_1$

$E_1{\lambda }_1-E_2{\lambda }_2=W({\lambda }_2-{\lambda }_1)$

$W=\frac{E_1{\lambda }_1-E_2{\lambda }_2}{{\lambda }_2-{\lambda }_1}$

Answer: $\frac{\left(E_1{\lambda }_1-E_2{\lambda }_2\right)}{\left({\lambda }_2-{\lambda }_1\right)}$