Physics - Geometrical Optics Question with Solution | TestHub

The power of the combination of lenses is given by the sum of their individual powers.

$P=P_1+P_2$

Substituting the given values:

$P=+2.50-3.75=-1.25$ D

The focal length $f$ of the combination is the reciprocal of the total power.

$f=\frac{1}{P}$

$f=\frac{1}{-1.25}$ m

$f=-0.8$ m

Converting to centimeters:

$f=-0.8\times 100=-80$ cm

Answer: -80 cm