To find the values of v for different values of v in case of concave mirror and to find the focal length. | Physics Practical Class 12 | Gaurav Kumar

 To find the values of v for different values of v in case of concave mirror and to find the focal length. 

Aim: -

To find the values of v for different values of v in case of concave mirror and to find the focal length. 

APPARATUS: -

Optical bench, two pins, upright, concave mirror, lens holder.

THEORY: -

            Here, 

                                f     =    focal length 

                                u    =    object distance

                                v    =    Image distance

OBSERVATIONS: -

1.    Rough focal length of the convave mirror  =   ................................ cm

2.    Length of the knitting needle,              x    =    .......................... cm

3.    Observed distance between the mirror and the object needle O when the knitting needle is introduced in between them, y = ....................... cm

4.    Observed distance between the mirror and the image needle I when he knitting needle is introduced in between them,     z    =    ................. cm

5.    Index error for u,     =    e1 = (y- x) = ........................ cm

      Index correction for u,                =    (-e1)    =    ...............cm

6.    Index error for v,     e2     =    (z - x)     =    ................... cm

       Index correction for v,        =    (-e2)    =    ................... cm

TABLE :     Determination of focal length

Mean value of f     =    ................ cm.

CALCULATIONS: -

Do yourself.

RESULT: -

The focal length of the given concave mirror as found using     

(i)    u     v/s    v graph     =    ............. cm

(ii)    1/ u    v/s    1/v graph     =    .............. cm

PRECAUTION: -

1.    The pole of concave mirror and tips of object needle and image needle must be at the same height.

2.    The uprights must be vertical.

3.    The object needle and the image needle should be clearly marked so that they can be distinguished.

4.    The distance between the eye and the image needle should be more than 25 cm.

5.    Index correction should be determined carefully.

6.    Parallax between the image needle and the image of the object needle should be removed tip to tip.