CBSE Class 10 Science 2019 · Paper 31/3/1 · Question 26(a)

1. Fix the concave mirror in a holder (stand) and place it near an open window, with its reflecting surface facing a distant object such as a tree or a building. 2. Place a white screen on a stand in front of the mirror, between the mirror and the window, slightly to one side so that it does not block the light from the object. 3. Move the screen back and forth until a sharp, clear image of the distant object (real, inverted and diminished) is obtained on it. 4. Mark the positions of the mirror and the screen on a metre scale and measure the distance between them: this distance is the approximate focal length of the mirror. Repeat and take the average.