Question

If both the lenses used for achromatic are of same material, then

• A. Chromatic is removed
• B. Chromatic cannot be removed
• C. Data insufficient
• D. None of these

Answer 1

The correct option is B Chromatic cannot be removed

If both the lenses used for achromatic are of same material then ${\omega }_1={\omega }_2$
So, from $\frac{{\omega }_1}{f_1}+\frac{{\omega }_2}{f_2}=0$, we have,
$\frac{1}{f_1}+\frac{1}{f_2}=0\Rightarrow \frac{1}{f}$ or$f=\infty$
Thus, the consideration behaves as a plane glass plate, so, the chromatism cannot be removed.