In a ray diagram, the three rays typically start from:

In a ray diagram, the three rays typically start from:

• A. Three different points on the object
• B. A focal point on the opposite side of the lens
• C. A focal point on the same side of the lens
• D. A single point on the object

Answer: (C)

The main idea is that in a lens ray diagram you determine the image of a point by drawing several rays that all originate from the same point on the object. From the top of the object, you draw three standard rays: one parallel to the principal axis (which later passes through the focal point on the far side), one through the center of the lens (which goes straight), and one through the focal point on the near side (which exits parallel to the axis). The image is where these rays intersect after the lens. So the starting point is a single point on the object, not multiple points or a focal point. The focal points set directions after the lens, not where the rays begin.

The main idea is that in a lens ray diagram you determine the image of a point by drawing several rays that all originate from the same point on the object. From the top of the object, you draw three standard rays: one parallel to the principal axis (which later passes through the focal point on the far side), one through the center of the lens (which goes straight), and one through the focal point on the near side (which exits parallel to the axis). The image is where these rays intersect after the lens. So the starting point is a single point on the object, not multiple points or a focal point. The focal points set directions after the lens, not where the rays begin.