Characteristics of Images
When you look into a mirror, the nature of the image can change depending on the mirror type and how far you are from it.
1. Concave Mirrors
Concave mirrors are versatile. The image formed depends heavily on the distance of the object.
- Object very close: The image is Erect (upright), Virtual, and Enlarged. (Used in shaving mirrors or dentist mirrors).
- Object far away: The image is Inverted (upside down) and can be larger or smaller than the object. It is a Real image (can be projected on a screen).
2. Convex Mirrors
Convex mirrors are much simpler. No matter where the object is placed:
- The image is always Erect (upright).
- The image is always Diminished (smaller than the object).
- The image is always Virtual (cannot be caught on a screen).
Summary Table
| Feature | Concave Mirror | Convex Mirror | Plane Mirror |
|---|---|---|---|
| Image Orientation | Erect (if close) or Inverted (if far) | Always Erect | Always Erect |
| Image Size | Enlarged or Diminished | Always Diminished | Same Size |
| View Area | Narrow | Wide Field of View | Normal |
Real-World Applications
Why are Side-View Mirrors Convex?
Side-view mirrors on vehicles are convex because:
- They always produce an erect image.
- They produce a diminished image, allowing a much wider field of view. This helps the driver see more traffic behind them.
Note: This is why they carry the warning “Objects in mirror are closer than they appear”.
Uses of Concave Mirrors
- Dentists: To see an enlarged image of teeth.
- Torches & Headlights: The bulb is placed near the mirror to create a powerful parallel beam of light.
- Solar Furnaces: To concentrate sunlight to a single point to generate heat.
Note
Real vs. Virtual Images
- Real Image: Formed when light rays actually meet. Can be captured on a screen (e.g., cinema screen). Always inverted.
- Virtual Image: Formed when light rays appear to meet. Cannot be captured on a screen. Always erect.