PPT1.1-Reflection and Mirrors

Experiment: Write "MIRROR" on a clean sheet of paper and place it in front of a plane mirror.
Topic: Geometric Optics: Reflection and Mirrors

Light as a Particle:
- Proposed by Isaac Newton in 1665, light consists of streams of particles called corpuscles.
Light as a Wave:
- Proposed by James Clerk Maxwell (1873) and Heinrich Hertz (1887), existence of electromagnetic waves.
Reflection of Light:
- Occurs when light rays bounce off a surface, such as a plane mirror.

Positioning of Light Rays:
- When an electromagnetic wave meets a reflecting surface, the direction of the reflected wave is determined by:
  - A: Angle of incidence
  - B: Intensity of the wave
  - C: Index of the medium
  - D: Material of the reflecting surface
Angle Between Ruler and its Image:
- Angle with vertical plane mirror is 30°, angle between ruler and image is also 30°.
Laws of Reflection:
- The angle of incidence (𝜽) equals the angle of reflection (𝜃).
- Incident ray, reflected ray, and normal line lie in the same plane.
- Definitions:
  - Incident Ray: Ray of light approaching the mirror.
  - Reflected Ray: Ray of light leaving the mirror.
  - Normal Line: Imaginary line perpendicular to the mirror surface.

Image Characteristics:
- When standing in front of a plane mirror, the image characteristics are:
  - A: Real, erect, and smaller than you
  - B: Real, erect, and the same size as you
  - C: Virtual, erect, and smaller than you
  - D: Virtual, erect, and the same size as you
Plane Mirrors:
- The image appears to be behind the mirror (virtual image).
- Height of the image (h') is equal to the height of the object (h): h' = h.
- Magnification (M):
  - M > 1: Image is larger than object.
  - M < 1: Image is smaller than object.
  - +M: Image is upright compared to the object.
  - -M: Image is inverted compared to the object.

Distance Between Object and Image:
- Example: A ball held 50 cm in front of a plane mirror; distance between the ball and its image is 100 cm.
Types of Spherical Mirrors:
- Concave/Converging Mirror:
  - Bulges away from light source; parallel incident rays converge or meet/intersect.
- Convex/Diverging Mirror:
  - Bulges towards light source; parallel incident rays diverge after reflection.

Important Points:
- Center of Curvature (C): Center of the sphere of which the mirror is part; distance known as the radius.
- Vertex (V): Center of the mirror.
- Focal Point/Focus (F): Point between center of curvature and vertex; distance known as the focal length (𝑓).
- Principal Axis (P): The horizontal line through the mirror's center.
Principal Rays in Curved Mirrors:
1. P – F ray
2. F – P ray
3. C – C ray
4. V ray

When object is between concave mirror and focal point:
- Options for characteristics:
  - A: Virtual, inverted, and larger than the object
  - B: Real, inverted, and larger than the object
  - C: Virtual, erect, and larger than the object
  - D: Real, erect, and larger than the object
Distance for Same Size Image:
- At what distance must an object be placed in front of a concave mirror for image size to equal the object size?
  - A: Less than half the focal length
  - B: Half the focal length
  - C: A focal length
  - D: Twice the focal length

Characteristics of Image in front of Convex Mirror:
- If the erect object is distanced greater than the focal length:
  - A: Real, inverted, and smaller than the object
  - B: Virtual, inverted, and larger than the object
  - C: Real, inverted, and larger than the object
  - D: Virtual, erect, and smaller than the object
Principal Rays in Convex Mirrors:
- Similar to concave mirrors:
  1. P – F ray
  2. F – P ray
  3. C – C ray

Concave Spherical Mirror:
- Focal length: 12 cm
- If object placed 6 cm in front, describe magnification and orientation of the image:
  - A: Magnification 0.67, image is inverted
  - B: Magnification 2, image is erect
  - C: Magnification 0.67, image is erect
  - D: Magnification 2, image is inverted.
Mirror Equation: A formula that relates the object distance, image distance, and focal length of spherical mirrors.

Convex Spherical Mirror Problem:
- Focal length: 12 cm.
- If object placed 6 cm in front:
  - A: Image located 4 cm behind the mirror
  - B: 12 cm behind the mirror
  - C: 12 cm in front of the mirror
  - D: 4 cm in front of the mirror.

Term: Reflection of Light
Definition: Occurs when light rays bounce off a surface, such as a plane mirror.
Term: Laws of Reflection
Definition: The angle of incidence equals the angle of reflection; incident ray, reflected ray, and normal line lie in the same plane.
Term: Incident Ray
Definition: Ray of light approaching the mirror.
Term: Reflected RayDefinition: Ray of light leaving the mirror.
Term: Normal LineDefinition: Imaginary line perpendicular to the mirror surface.
Term: Virtual ImageDefinition: The image appears to be behind the mirror, and the height of the image is equal to the height of the object (h' = h).
Term: Concave MirrorDefinition: Bulges away from the light source; parallel incident rays converge.
Term: Convex MirrorDefinition: Bulges towards the light source; parallel incident rays diverge after reflection.
Term: Focal Point (F)Definition: Point between the center of curvature and vertex of a mirror.
Term: Magnification (M)Definition: Ratio that indicates the size of the image relative to the object size; determined by image height over object height.