2.2.4 Lenses

• Concave lenses are thinner at the center and cause light rays to diverge
• What happens to parallel light rays when they pass through a concave lens?

  They diverge
• Where are convex lenses used in optical systems?

  Magnifying glasses
• Match the lens property with its type:

  Shape | Thicker at center ↔️ Convex

  Effect on Light | Diverge ↔️ Concave
• In which optical devices are convex lenses commonly used?

  Cameras and projectors
• A convex lens always forms a real image.

  False
• Match the type of ray with its behavior in a convex lens:

  Parallel Ray ↔️ Passes through focal point

  Center Ray ↔️ Continues straight

  Focus Ray ↔️ Bends parallel to principal axis
• Match the lens type with its effect on light:

  Concave lens ↔️ Diverges light rays

  Convex lens ↔️ Converges light rays
• A concave lens diverges light rays.
• Match the lens type with its typical use:

  Concave Lens ↔️ Camera viewfinders

  Convex Lens ↔️ Magnifying glasses
• Convex lenses are used in projectors to focus light and create a clear image.
• Steps to describe the path of light rays through a concave lens:

  1️⃣ Light rays enter the lens

  2️⃣ Light rays diverge

  3️⃣ Light rays appear to originate from a focal point
• Ray diagrams are graphical tools used to illustrate how light rays travel through lenses.
• A ray passing through the center of a lens continues unchanged without bending.
• Light rays diverge when passing through a concave lens, whereas they converge when passing through a convex lens.
• A lens is a transparent object used to refract light and focus it to a point
• What is the effect of a convex lens on light rays?

  They converge
• Concave lenses are used in telescopes to create a wider field of view
• Light rays diverge when they pass through a concave
• What is the shape of a convex lens?

  Thicker at the center
• What is the shape of a convex lens?

  Thicker at the center
• A convex lens is thicker at the center
• What is the focal length of a concave lens?

  Negative
• The shape of a concave lens is thinner at the center
• Steps to describe the path of light rays through a convex lens:

  1️⃣ Light rays enter the lens

  2️⃣ Light rays converge

  3️⃣ Light rays focus at a focal point
• What happens to light rays when they pass through a convex lens?

  They converge
• A convex lens is thinner at the edges than at the center.


  True
• Convex lenses always produce virtual images.

  False
• Concave lenses have a positive focal length.

  False
• Convex lenses can produce both real and virtual images.

  True
• Concave lenses have a negative focal length.

  True
• A ray aimed towards the focal point of a concave lens bends parallel to the principal axis.

  True
• The focal length of a concave lens is always negative
• The focal length of a convex lens is always positive
• A concave lens is thicker at the edges
• What is the formula for magnification of a convex lens?

  d_i/d_o
• What type of image is formed by a concave lens?

  Virtual, upright, smaller
• What is the main purpose of a lens?

  To refract and focus light
• Concave lenses are used in magnifying glasses.

  False
• Convex lenses are thicker at the edges than at the center.

  False