A parallel beam of light coming from an object, after passing through a converging len. will wet at a ,- int on the - -the. side of the 1. ni. At the point where thewe rays Duvet a image or the . byoct i. formea. This point is called the principal foc _ or the len. the distance In asu ed from the center of the leas to the princi :al rocus is calle. the f- cal length .I the lens the purpose of this lab is to measure the focal length of a converging luna. A lightec object is laced at a distance U from the lens and a clear image on it i. ol tainea on a screen laced at a cistance from the lens Object image screen 2F F 2F Focal Length The focal length of the lens is calculated using the form la U. U V