Physics - Geometrical Optics Question with Solution | TestHub

When two lenses are separated by some distance$x$, then equivalent power

$P=P₁+P₂-xP₁P₂$

$\therefore P=5+5-x\times 5\times 5$

$or P=10-25x$

Power$P$will be negative if 10-25x will be negative

$ie, 25x>10$

$or x>\frac{10}{25}$

$or x>\frac{10}{25}\times 100 \mathrm{cm}$

$or x>40\mathrm{ }\mathrm{cm}$