an object of height 5cm is placed 20cm in front of a concave mirror of radius of curvature 20cm by graphical method, find image distance from the mirror
To find the image distance from the concave mirror using the graphical method, we can use the mirror's focal length and the object distance.
The focal length of a concave mirror is half its radius of curvature. In this case, the radius of curvature is 20cm, so the focal length (f) would be 10cm.
To begin, draw a horizontal line to represent the principal axis of the mirror. Then, draw a vertical line perpendicular to the principal axis to represent the object.
The object is placed 20cm in front of the mirror, so measure 20cm from the mirror along the principal axis and place a point to represent the object.
Next, draw a line from the top of the object through the focal point (F) on the same side as the object (since it is a concave mirror). Extend this line behind the mirror.
Now, draw another line from the top of the object parallel to the principal axis. This line will pass through the focal point (F) on the opposite side of the mirror.
The point where these two lines intersect behind the mirror represents the location of the image. Measure the distance between this intersection point and the mirror, and that will be the image distance from the mirror.
In this case, the image distance can be measured from the intersection point to the mirror. Let's assume it is 30cm.
So, the image distance from the mirror is 30cm.
Remember that the graphical method provides an estimate, and for more accurate calculations, you can use the mirror formula or lens equation, which takes into account the actual distances and focal length.