physics

• Light


  A form of energy that enables us to see
• Reflection of Light


  • Bouncing back of the light to the same medium
  • Angle of incidence is equal to angle of reflection
  • The incident ray, reflected ray lies on the same plane
• White colour


  • When all colours reflect back, it is visible to our eyes
• Black colour


  • Absence of all colours
• Real Images


  The image that can be taken on the screen
• Virtual Images


  The image that cannot be taken on the screen, always erect
• Concave mirror


  Converging mirror
• Convex mirror


  Diverging mirror
• Centre of curvature


  The centre of the sphere of which the mirror is a part
• Radius of curvature


  The radius of the sphere of which the mirror is a part
• Pole


  The centre of the mirror
• Principal axis


  The line joining the centre of curvature and pole
• Laws of Reflection


  1. When a ray of light is thrown parallel to the principal axis, after reflection it will pass through the focus

  2. If a ray of light passes through the focus of the mirror, after reflection it becomes parallel to the principal axis

  3. If the light passes through the centre of curvature, after reflection it retraces its path
• Focal length


  The distance between the pole and the principal focus of the spherical mirror
• Radius of curvature (R)


  2 times the focal length (f)
• Concave mirror


  • Positive focal length
  • Positive radius of curvature
• Convex mirror


  • positive focal length
  • positive radius of curvature
• Dotted lines in convex mirror depict imaginary lines
• Ray passing through principal axis


  Concave mirror: Passes through focus

  Convex mirror: Becomes parallel to principal axis
• Ray passing through focus

  Concave mirror: Becomes parallel to principal axis

  Convex mirror: Becomes parallel to principal axis
• Ray passing through centre of curvature

  Concave mirror: Retraces its path

  Convex mirror: Retraces its path
• Ray passing through oblique

  Concave mirror: Forms real image

  Convex mirror: Forms virtual image
• Concave mirror forming virtual image

  Object is between focus and pole
• Position of object


  Determines position of image in concave mirror
• What is the primary function of the human eye?


  The human eye enables us to see objects around us.

  
• How does the lens in the human eye function?

  The lens in the human eye adjusts its curvature to focus light on the retina.

  
• What happens to light as it enters the human eye?


  Light enters the eye through the cornea and is refracted to form an image on the retina.

  
• What is the diameter of the human eyeball?

  The diameter of the human eyeball is approximately 2.3 cm.
• What role does the iris play in the human eye?

  The iris controls the size of the pupil and regulates the amount of light entering the eye.
• What is the function of the retina in the human eye?

  The retina contains light-sensitive cells that generate electrical signals sent to the brain.
• What happens when light-sensitive cells in the retina are activated?

  They generate electrical signals that are sent to the brain for interpretation.
• What is the least distance of distinct vision for a young adult with normal vision?

  The least distance of distinct vision is about 25 cm.
• What is the far point of the human eye with normal vision?

  The far point is infinity for a normal eye.
• What condition occurs when the crystalline lens becomes milky and cloudy?

  This condition is called cataract, which can cause partial or complete loss of vision.
• Why do humans have two eyes instead of one?

  Having two eyes provides a wider field of view and enhances depth perception.
• What is the role of the ciliary muscles in the eye?

  The ciliary muscles modify the curvature of the eye lens to adjust its focal length.
• What is accommodation in the context of the human eye?

  Accommodation is the ability of the eye lens to adjust its focal length for clear vision at different distances.

  
• What is myopia also known as?

  Myopia is also known as near-sightedness.
• How is myopia corrected?

  Myopia can be corrected using a concave lens of suitable power.
• What is hypermetropia also known as?

  Hypermetropia is also known as far-sightedness.