Lenses and Ray Diagrams

Question

Lenses and Ray Diagrams
The orientation and magnification of an image depend on the object's position in relation to the focal point and the lens. In a convex lens, if an object is closer to the lens than the focal point, a virtual image forms. If the object is farther from the lens than the focal point, a real image forms. A concave lens always forms an image that is virtual, right side up, and smaller than the actual image.

Real Image Virtual Image
Image is inverted
Rays of light actually meet
Forms below principal axis
Image is upright
Rays of light appear to meet
Forms above principal axis
The image that forms when an object is outside the focal point in a convex and concave lens is shown.

Two incomplete models show the object inside the focal point of a convex and concave lens.

Two-Part Question
Multiple Choice Question
The following question has two parts. First, answer Part A. Then, answer Part B.

Part A:

Which choice shows the completed ray diagram for Model 2?

A.

B.

C.

D.

Multiple Choice Question
Part B:

Which best describes the image from the choice in Part A?

A.
The image is upright and larger.

B.
The image is upright and smaller.

C.
The image is upside down and larger.

D.
The image is upside down and smaller.

Answer 1

To analyze the questions you provided, let’s break down the concepts involved with both convex and concave lenses.

Part A: Completed Ray Diagram for Model 2

1. Convex Lens (Model 1):

   • When an object is placed within the focal length of a convex lens, the image formed is virtual, upright, and larger. The ray diagram would typically depict:
     • A ray parallel to the principal axis diverging as if it comes from the focal point on the same side as the object.
     • A ray passing through the optical center of the lens continues in a straight line.
     • The point where these rays appear to diverge creates a virtual image above the principal axis.

2. Concave Lens (Model 2):

   • When an object is placed anywhere in front of a concave lens, the image produced is virtual, upright, and smaller than the object. The ray diagram would typically illustrate:
     • A ray parallel to the principal axis diverges, appearing to come from the focal point on the same side as the object.
     • A ray heading towards the focal point on the lens gets refracted and runs parallel to the principal axis.
     • The intersection (or apparent intersection) of those rays forms a virtual image above the principal axis.

Since I do not have access to the visuals of the diagrams presented in the multiple choices (A, B, C, D), I cannot directly identify which choice shows the completed ray diagram for Model 2. However, you should select the ray diagram that represents these characteristics for a concave lens.

Part B: Description of the Image from Choice in Part A

• Given that we are referring to a concave lens, the image formed is:
  • Upright: Virtual images formed by concave lenses are always upright.
  • Smaller: The image produced by a concave lens is smaller than the object.

Thus, the correct answer for Part B would be: B. The image is upright and smaller.

Make sure to choose the ray diagram that reflects these properties for Part A, and check if it aligns with the description in Part B.