Design an activity using concave mirror to prove that a converging in nature also state a method to find its focal length
Answers
Answer:
Activity:
1. Hold a concave mirror in your hand and direct its reflecting surface
towards the Sun.
2. Direct the light reflected by the mirror on to a sheet of paper held
close to the mirror.
3. Move the sheet of paper back and forth gradually until you find
on the paper sheet a bright, sharp spot of light.
4. Hold the mirror and the paper in the same position for a few
minutes.
5. The paper at first begins to burn producing smoke. Eventually it
may even catch fire.
6. The light from the Sun is converged at a point, as a sharp, bright spot by the mirror.
7. This point is the focus of the concave mirror. The heat produced due to
the concentration of sunlight ignites the paper.
This activity shows that concave mirrors are convergent in nature.
Answer:
The following activity can be used to determine the principal focus and approximate focal length of a concave mirror.
(1) Place the mirror vertically on a table.
(2) Place an object (a pencil) in front of the mirror and move it towards and away from the mirror.
(3) Find the approximate spot where the reflection of the object changes from upright to upside down. This point is the focus of the mirror. Measure the distance between this point and the mirror. This length is the focal length of the mirror.