PHYSICS - CHAP TER 2: LENSES (
ലെൻസുകൾ )
Class 10 SCERT Kerala State Syllabus • Complete Short Study Notes
1. What is a Lens? (എന്താണ് ലെൻസ് ?)
A lens is a transparent optical medium bounded by two spherical surfaces or one plane surface and one
spherical surface.
★ Main Types of Lenses:
1. Convex Lens ( കാൺ വെക്സ് ലെൻസ്): Thick at the middle, thin at the edges. Also
called Converging Lens.
2. Concave Lens ( കാൺ കവെ് ലെൻസ്): Thin at the middle, thick at the edges. Also
called Diverging Lens.
Convex Lens (Converging) Concave Lens (Diverging)
Fig 1.1: Basic Shapes of Convex and Concave Lenses
2. Technical Terms Related to Lenses
• Centre of Curvature (C): The centre of the spherical surface of which the lens forms a part. (Since a
lens has 2 surfaces, it has 2 centers: C and C ).
1 2
• Radius of Curvature (R ): The radius of the sphere of which the surface of the lens forms a part.
• Principal Axis: The imaginary line joining the two centres of curvature (C and C ).
1 2
• Optic Centre (O): The central point of a lens. A ray of light passing through 'O' passes without any
deviation.
ലെൻസുകൾ )
Class 10 SCERT Kerala State Syllabus • Complete Short Study Notes
1. What is a Lens? (എന്താണ് ലെൻസ് ?)
A lens is a transparent optical medium bounded by two spherical surfaces or one plane surface and one
spherical surface.
★ Main Types of Lenses:
1. Convex Lens ( കാൺ വെക്സ് ലെൻസ്): Thick at the middle, thin at the edges. Also
called Converging Lens.
2. Concave Lens ( കാൺ കവെ് ലെൻസ്): Thin at the middle, thick at the edges. Also
called Diverging Lens.
Convex Lens (Converging) Concave Lens (Diverging)
Fig 1.1: Basic Shapes of Convex and Concave Lenses
2. Technical Terms Related to Lenses
• Centre of Curvature (C): The centre of the spherical surface of which the lens forms a part. (Since a
lens has 2 surfaces, it has 2 centers: C and C ).
1 2
• Radius of Curvature (R ): The radius of the sphere of which the surface of the lens forms a part.
• Principal Axis: The imaginary line joining the two centres of curvature (C and C ).
1 2
• Optic Centre (O): The central point of a lens. A ray of light passing through 'O' passes without any
deviation.
