The Magic Behind Mirrors: Complete Guide to Image Formation
Master all 6 cases of concave mirrors and convex mirror image formation with detailed ray diagrams and JEE applications.
Why Mirror Image Formation is Crucial for JEE
Spherical mirrors form the foundation of geometrical optics in JEE Physics. Understanding image formation helps in:
- Direct numerical problems using mirror formula
- Ray diagram interpretation questions
- Application-based problems in optical instruments
- Advanced concepts like magnification and sign convention
๐ Key Terminology & Sign Convention
Important Points:
- Pole (P): Center of the mirror surface
- Center of Curvature (C): Center of the sphere
- Focus (F): Midpoint between P and C
- Focal Length (f): Distance PF = R/2
Sign Convention:
- Object distance (u): Always negative
- Image distance (v): Sign depends on image nature
- Focal length (f): Negative for concave, positive for convex
- Height: Positive upward, negative downward
Object at Infinity
๐ Ray Diagram:
Ray 1: Parallel to principal axis โ Passes through focus
Ray 2: Through center of curvature โ Retraces path
๐ Image Characteristics:
Position: At focus F
Nature: Real and inverted
Size: Highly diminished
Magnification: Almost zero
Object Beyond Center of Curvature
๐ Ray Diagram:
Ray 1: Parallel to principal axis โ Through focus
Ray 2: Through focus โ Parallel to principal axis
๐ Image Characteristics:
Position: Between F and C
Nature: Real and inverted
Size: Diminished
Magnification: < 1
Object at Center of Curvature
๐ Ray Diagram:
Ray 1: Parallel to principal axis โ Through focus
Ray 2: Through pole โ Reflects with equal angle
๐ Image Characteristics:
Position: At C (same point)
Nature: Real and inverted
Size: Same as object
Magnification: -1
๐งฎ Mirror Formula & Magnification
Mirror Formula:
Where: f = focal length, v = image distance, u = object distance
Magnification:
Where: hแตข = image height, hโ = object height
๐ Problem-Solving Strategies
For Concave Mirrors:
- Always start with sign convention
- Object beyond C โ image between F and C
- Object between F and P โ virtual image
- At C โ image same size, inverted
For Convex Mirrors:
- Always virtual, erect, diminished
- Image between P and F
- Wide field of view
- Used in rear-view mirrors
Cases 4-6 Available in Full Version
Includes object between F&C, at F, between P&F, and convex mirror cases with detailed ray diagrams
๐ Quick Self-Test
Try these JEE-level problems to test your understanding:
1. An object is placed 30cm from a concave mirror of focal length 15cm. Find image position and nature.
2. A convex mirror has radius 40cm. Where is the image when object is at 20cm?
3. Draw ray diagram for object between F and P in concave mirror.
Ready to Master All Mirror Cases?
Get complete access to all 6 concave mirror cases and convex mirrors with interactive ray diagrams