Concepts to Remember on the : Viewing Objects- Eyes as an Optical Instrument - Ray Optics and Optical Instruments:

Concepts of Ray Optics:

1. Laws of Reflection:

• Incident angle is equal to the reflected angle.

2. Laws of Refraction:

• Snell’s Law: n₁ sin(i) = n₂ sin(r), where n₁ and n₂ are indices of refraction, i is the incident angle, and r is the refracted angle.

3. Refraction at a Plane Surface:

• Light bends as it crosses from one medium to another.

4. Refraction at a Spherical Surface:

• Converging and diverging lenses can form images.

5. Thin Lens Formula:

• 1/f = 1/v - 1/u, where f is the focal length, v is the image distance, and u is the object distance.

6. Magnification (M):

• m = v/u, where m is the magnification, v is the image distance, and u is the object distance.

Optical Instruments:

1. Simple Microscope:

• Uses a single converging lens to magnify objects.

2. Compound Microscope:

• Combines two or more lenses to achieve much greater magnification than a simple microscope.

3. Reflecting Telescope:

• Uses mirrors to collect and focus light from distant objects.

4. Refracting Telescope:

• Uses lenses to collect and focus light from distant objects.

5. Camera:

• Captures images on a light-sensitive film or digital sensor using a lens to focus light.

6. Human Eye:

• a.) Structure:

  • Cornea: Transparent outer layer that covers and protects the eye.
  • Pupil: Adjustable opening that controls the amount of light entering the eye.
  • Lens: Flexible structure that changes shape to focus light on the retina.
  • Retina: Light-sensitive inner layer that contains photoreceptor cells.
  • Blind spot: Area on the retina where there are no photoreceptors, resulting in a small region of no vision.

• b.) Functioning:

  • Focusing: The cornea and lens work together to focus light onto the retina.
  • Accommodation: The lens changes shape to fine-tune the focus for objects at different distances.