To determine where the image is, it is very helpful to draw a ray diagram. Send rays out from the object, reflect them from the mirror, and see where they go. The image is where the rays intersect.

Rays that are easy to draw include:

• The parallel ray goes from the tip of the object horizontally to the mirror. It reflects off the mirror and passes through the focal point.
  
  
• The chief ray is a line connecting the tip of the object and the center of curvature. This ray will hit the mirror at a 90° angle, reflecting back the way it came.
  
  
• The focal ray is a mirror image of the parallel ray. It goes from the tip of the object through (or towards) the focal point, and reflects off the mirror horizontally.
  
  
• Another ray is one that goes from the tip of the object to the mirror at the principal axis. The reflected ray is on the other side of the principal axis at the same angle.

Only two rays are necessary to locate the image on a ray diagram, but it's useful to add at least one more as a check.