Question

10 ssc science practical to obtain the focal length of convex lens observation table

Answer 1

AIM: To determine the focal length of convex lens.

APPARATUS: Convex lens, optical bench, objects and image pins, meter rule.

$FURMULA \: of \: focal \: lenght \: of \: convex \: lens = \frac{vu}{v - u}$

PROCEDURE:

1) Obtain a sharp image of a distant object on the wall of the laboratory with the convex lens. The distance between the convex lens and the image, measured roughly with a

meter rule would give the approximate focal length of the lens.

2) Arrange the lens in lens holder of the optical bench. Now place the object pin. Object pin should be at zero.

3) Move the image pin and adjust its position till the parallax between the image pin and object pin is removed.

4) Record the distance u between object pin and lens and distance v between image pin

and lens.

5) Repeat the process three times by changing the object distance u.

6) Calculate focal length of given convex lens with formula.

We can fill it out by yourself.

Answer 2

Answer:

it is obtained by the formula

1/f = 1/v + 1/u