As shown in Fig, when a ray of light is incident on a mirror, it gets reflected in accordance with the following laws of reflection:
First law: The incident ray, the reflected ray and the normal at the point of incidence all lie in the same plane.
Fig. Reflection in a plane mirror Second law: The angle of incidence (i) is equal to the angle of reflection (r) i.e.,
∠i = ∠r.
Mirror is a highly polished and smooth surface to reflect a good fraction of light incident on it. The surface may be metallic or an ordinary glass plate coated with a thin silver layer.
The commonly used mirrors acording to the reflecting mirrors are of three types:
1. Plane mirror
2. Spherical mirror
3. Paraboidal mirror.
Properties of images formed by a plane mirrors:
1. The image formed by a plane mirror is virtual and erect.
2. Image formed is of the same size as the object.
3. The image is formed as far behind the mirror as the object is in front of it i.e., object distance is equal to the image distance.
4. Image is laterally inverted i.e., image is inverted sideways with respect to the object.
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Real image |
Virtual image |
|
1. Here the rays actually meet at the point after refraction or reflection. |
1.A virtual image is formed when, the rays appear to converge. |
|
2. Real image can be obtained on the screen. |
2. It cannot be obtained on the screen. |
|
3. Real image is always inverted. |
3. Real image is always erect. |
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