Question

A horizontal ruler from 0 to 100. An image of an upward pointing arrow in a frame, at 0. A double convex lens at 100. X marked in the center of the ruler.

What does the “X” on the horizontal line represent?
Draw the ray diagram in your notes, showing only the principal rays. Explain why you don’t need to draw more rays.
Where will the image appear? On the left or on the right of the lens? At which mark on the ruler?
How will the image look? Upright or inverted? Same size, larger, or smaller?

Answer 1

The 'X' mark likely represents the focal point of a double convex lens. The image formed by a convex lens for an object placed beyond the focal length will appear on the right side of the lens, inverted and varying in size depending on the object's distance.

Step-by-step explanation:

In the described scenario, the X on the horizontal ruler most likely signifies the position of the focal point of a double convex lens. Ray tracing involves using a few simple rules to determine the location and nature of the image formed by the lens. When tracing the rays, we use three principal rays from a single point on the object: the first enters the lens parallel to its axis and passes through the focal point on the opposite side, the second passes through the center of the lens, and the third heads towards the focal point on the same side of the lens and exits parallel to the axis. However, only two rays are necessary to accurately locate the image.

Based on the description, the image will appear on the right of the lens because rays converge after passing through a convex lens. Considering that the rules specify that parallel rays either pass through the focal point or exit parallel to the lens after entering through the focal point, the image is formed on the opposite side of the lens from the object. Consequently, the exact position on the ruler where the image appears depends on the object distance (do), image distance (di), and the lens's focal length (f), which can be determined using the lens formula.

For an object placed beyond the focal length of a convex lens, the image formed would typically be inverted and can be larger or smaller than the object depending on the object's distance from the lens. If the object is positioned at twice the focal length, the image will appear at the same size as the object but inverted. If the object is closer to the lens, but still beyond the focal length, the image will appear larger. Conversely, if the object is placed further away from the lens than this point, the image would be smaller.