Question

can you find the focal length of a concave lens by forming the image of a distant object on a screen. give reason ​

Answer 1

I HOPE IT'S HELPFULL

Answer 2

Answer:

The ends of the ruler get damaged with use and its zero may not be visible. To measure the length of an object with such a ruler, the object is placed close to a specific markings on the ruler and positions of both ends of the object are read on the ruler.

The difference of the two readings gives the length of the object. In fig, the reading on ruler at the end X is 1.0cm and at the end Y is 4.3cm. So the length of the rod XY is 4.3−1.0=3.3cm.