Final answer:
To see the back of your head with mirrors, a minimum of two mirrors is required, positioned in such a way that one mirror reflects your image into the other, adhering to the Law of Reflection.
Step-by-step explanation:
To see the back of your head using mirrors, you need at least two mirrors positioned at an angle relative to one another. This setup allows you to look into one mirror which reflects the image into the other mirror, thereby giving you a view of the back of your head. The minimum number of mirrors needed for this task is two.
Law of Reflection
The Law of Reflection dictates that the angle of incidence is equal to the angle of reflection, which is essential in positioning the mirrors correctly to see the back of your head. If you stand between the two mirrors and adjust the angle, you can utilize the law to get the reflection from one mirror to bounce into the other and then to your eyes.
For instance, if you stand facing a mirror with another mirror behind you, you can see the back of your head. This is because the mirror in front of you will reflect the image of the back of your head from the second mirror, which in turn reflects the back of your head originally. The arrangement forms a periscopic effect, enabling you to view parts of yourself that would otherwise be out of sight.