Lecture Notes: Mirrors in General Physics

Introduction

• Topic: Mirrors in General Physics
• Focus on Algebra-based Physics
• Current Chapter: Mirrors (will cover lenses next)
• Types discussed: Plain and Spherical Mirrors
• Spherical Mirrors include Concave and Convex Mirrors

Key Concepts

Reflection and Refraction

• Previous chapter focused on these concepts

Mirrors

• Types:
  • Plain Mirrors
  • Spherical Mirrors (Concave and Convex)

Plain Mirrors

• Object Distance (p): Distance from the mirror to the object
• Image Distance (q): Distance from the mirror to the image
• Ray Diagrams: Used to discover image formation
  • Two key rays:
    • Head-on ray reflects directly
    • Ray through midpoint demonstrating law of reflection
• Image Characteristics:
  • Always Virtual
  • Upright
  • Object Distance = Image Distance
  • Magnification is 1 (same size as object)
  • Left-Right Reversal is observed

Spherical Mirrors

Concave Mirrors

• Scenarios:
  • Object Distance > Focal Length: Real, inverted image
  • Object Distance < Focal Length: Virtual, upright image
• Focal Length (f):
  • Half the Radius of Curvature
• Mirror Equation: [ \frac{1}{p} + \frac{1}{q} = \frac{1}{f} ]
• Ray Diagrams:
  • Ray parallel to principal axis reflects through the focal point
  • Ray through the focal point reflects parallel
  • Ray to principal axis reflects back identically

Convex Mirrors

• Characteristics:
  • Always Virtual and Upright
  • Image appears smaller than the object (Magnification < 1)
• Focal Length is negative
• Ray Diagrams:
  • Ray parallel appears to come from the focal point
  • Ray towards focal point becomes parallel

Image Characteristics

• Magnification (M):
  • [ M = - \frac{q}{p} ]
  • Positive: Upright
  • Negative: Inverted
  • Absolute value > 1: Larger image
  • Absolute value < 1: Smaller image

Practical Examples

• Concave Mirror Demos:

  • Changing object distance affects image form (inverted or upright)
  • At focal distance, image becomes infinitely large

• Convex Mirror Demos:

  • Image stays upright and virtual irrespective of object position

Problem Solving with Equations

• Example Calculations:
  • Calculating image location (q), Magnification (M)
  • Determining real/virtual and upright/inverted status

Conclusion

• Understanding of mirrors is crucial to grasping the basics of optics
• Knowing how to balance real and virtual images aids in practical applications

If you found this lesson helpful, consider reviewing and practicing with problem sets. Happy studying!