Opticsreflection Of Light And Formation Of Images
Concepts to Remember on Reflection of Light and Formation of Images
1. Laws of reflection:
- The incident ray, the normal to the surface at the point of incidence, and the reflected ray all lie in the same plane.
- The angle of reflection is equal to the angle of incidence.
2. Mirror equation:
- 1/f = 1/d_o + 1/d_i
- where f is the focal length, d_o is the object distance, and d_i is the image distance.
3. Formation of images by plane and spherical mirrors:
- Real images: Formed by the convergence of reflected rays. Can be projected onto a screen.
- Virtual images: Formed by the divergence of reflected rays. Cannot be projected onto a screen.
4. Magnification:
- The ratio of the image height to the object height.
- M = h_i/h_o = -d_i/d_o
5. Reflection from curved surfaces:
- Converging mirrors (concave): Cause rays to converge at a single point.
- Diverging mirrors (convex): Cause rays to diverge as if they were coming from a virtual point.
6. Focal length:
- The distance between the mirror and the point where parallel rays converge for a converging mirror or the point from which parallel rays appear to diverge for a diverging mirror.
7. Sign convention for spherical mirrors:
- Distances are positive if measured in the direction of the principal axis and negative if measured in the opposite direction.
- Object distances are negative for virtual objects.
- Image distances are negative for virtual images.
8. Ray diagrams for the formation of images by spherical mirrors:
- Used to graphically determine the location and characteristics of images formed by spherical mirrors.
9. Types of mirrors:
- Concave mirrors: Converging mirrors with a reflecting surface curved inward.
- Convex mirrors: Diverging mirrors with a reflecting surface curved outward.
10. Uses of mirrors:
- Shaving mirrors: Allow for a person to see their face clearly.
- Car rearview mirror: Allow drivers to see the area behind their car.
- Telescope: Used to magnify distant objects.