Question Number 133281 by aurpeyz last updated on 20/Feb/21
$${an}\:{object}\:{placed}\:\mathrm{20}{cm}\:{from}\:{a}\:{con}− \\ $$$${verving}\:{lens}\:{forms}\:{a}\:{mavnified}\:{clear} \\ $$$${image}\:{on}\:{the}\:{screen}.\:{when}\:{the}\:{lens} \\ $$$${is}\:{moved}\:\mathrm{20}{cm}\:{towards}\:{the}\:{screen} \\ $$$${a}\:{smaller}\:{clear}\:{image}\:{is}\:{formed}\:{on} \\ $$$${the}\:{screen}.\:{calculate}\:{the}\:{focal}\:{length} \\ $$$${of}\:{the}\:{lens} \\ $$